Catoptric objectives and systems using catoptric objectives

ABSTRACT

In general, in one aspect, the invention features an objective arranged to image radiation from an object plane to an image plane, including a plurality of elements arranged to direct the radiation from the object plane to the image plane, wherein the objective has an image side numerical aperture of more than 0.55 and a maximum image side field dimension of more than 1 mm, and the objective is a catoptric objective.

CROSS-REFERENCE TO RELATED APPLICATIONS

Under 35 U.S.C. §120, this application is a continuation of U.S. Ser.No. 13/183,823, filed Jul. 15, 2011, now U.S. Pat. No. 8,317,345, whichis a continuation of U.S Ser. No. 12/700,169, filed Feb. 4, 2010, nowU.S. Pat. No. 8,004,755, which is a continuation of U.S. Ser. No.11/317,851, filed Dec. 22, 2005, now U.S. Pat. No. 7,682,031, the entirecontents of which are hereby incorporated by reference. U.S. Ser. No.11/317,851 claims benefit under 35 U.S.C. §119(e)(1) of U.S. ProvisionalApplication No. 60/665,036, filed Mar. 24, 2005, U.S. ProvisionalApplication No. 60/695,455, filed Jun. 30, 2005, and U.S. ProvisionalApplication No. 60/698,909, filed Jul. 13, 2005. U.S. Ser. No.11/317,851 claims priority under 35 U.S.C. §119 to German PatentApplication No. DE 10 2004 063 313.4, filed Dec. 23, 2004, and GermanPatent Application No. DE 10 2005 042 005.2, filed Sep. 5, 2005.

TECHNICAL FIELD

This disclosure relates to catoptric projection objectives and tosystems that use catoptric projection objectives.

BACKGROUND

Projection objectives are widely used in microlithography to transfer apattern from a reticle to a substrate by forming an image of the reticleon a layer of a photosensitive material disposed on the substrate. Ingeneral, projection objectives fall into three different classes:dioptric objectives; catoptric objectives; and catadioptric objectives.Dioptric objectives use refractive elements (e.g., lens elements) toimage light from an object plane to an image plane. Catoptric objectivesuse reflective elements (e.g., mirror elements) to image light from anobject plane to an image plane. Catadioptric objectives use bothrefractive and reflective elements to image light from an object planeto an image plane.

SUMMARY

In general, in one aspect, the invention features an objective arrangedto image radiation from an object plane to an image plane. The objectiveincludes a plurality of elements arranged to direct the radiation fromthe object plane to the image plane. The objective has an image sidenumerical aperture of more than 0.55 and a maximum image side fielddimension of more than 1 mm, and the objective is a catoptric objective.

In general, in another aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane. The objective has animage side numerical aperture of more than 0.55, a distance between theobject plane and the image plane is less than 2 m, and the objective isa catoptric objective.

In general, in a further aspect, the invention features an objectivearranged to image radiation of wavelength λ from an object plane to animage plane. The objective includes a plurality of mirrors arranged todirect the radiation from the object plane to the image plane. Theobjective has an image side numerical aperture of more than 0.55 and amaximum image side field dimension of more than 1 mm, and λ is about 100nm or less.

In general, in another aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane, the plurality ofelements including a first element, a second element, and a thirdelement, where each of the first, second, and third elements have anopening for passage of the radiation from the object plane to the imageplane. The objective has an image side numerical aperture of more than0.55 and the objective is a catoptric objective.

In general, in a further aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane, the plurality ofelements including a first element and the first element does not havean opening. The objective has an image side numerical aperture of morethan 0.55, and the objective is a catoptric objective.

In general, in another aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane, the plurality ofelements including a first element and a second element, where the firstelement does not have an opening and the second element does have anopening for passage of the radiation from the object plane to the imageplane. The objective has a field independent obscuration related to theopening that is less than 30% of an aperture radius at a pupil plane andhas an image side numerical aperture of about 0.4 or more, and theobjective is a catoptric objective.

In general, in a further aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane where, for ameridional section of the objective, the radiation has a maximum angleof incidence on a surface of each of the elements of less than 22°. Theobjective has an image side numerical aperture of more than 0.4 and theobjective is a catoptric objective.

In general, in another aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane, the plurality ofelements including a first element and the first element has an openingfor passage of the radiation from the object plane to the image plane.The objective has an image side numerical aperture of more than 0.55 andthe objective is a catoptric objective.

In general, in a further aspect, the invention features an objectivearranged to image radiation of wavelength λ from an object plane to animage plane. The objective includes ten elements arranged to direct theradiation from the object plane to the image plane. The objective is acatoptric objective and λ is about 800 nm or less.

In general, in another aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane, the plurality ofelements comprising a first element, a second element, a third element,a fourth element, and a fifth element, where the first, second, third,and fourth elements each include an opening for passage of the radiationfrom the object plane to the image plane and the fifth element does notinclude an opening. The objective is a catoptric objective.

In general, in a further aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane, the plurality ofelements comprising a first element and a second element, where thefirst element does not include an opening and the second element has aconcave surface and is arranged so that the radiation contacts theconcave surface and the second element is the second to last element ina path of the radiation from the object plane to the image plane. Theobjective is a catoptric objective.

In general, in another aspect, the invention features an objectivearranged to image radiation of wavelength λ from an object plane to animage plane. The objective includes a first group of mirrors arranged toimage the radiation from the object plane to a first intermediate-imageplane, the first group of mirrors comprising a first mirror where thefirst mirror does not include an opening for passage of the radiationfrom the object plane to the image plane; and a second group of mirrorsarranged to image the radiation from the intermediate-image plane to theimage plane, the second group of mirrors comprising a second mirror anda third mirror, where the second and third mirrors each include aconcave surface and an opening for passage of the radiation from theobject plane to the image plane, the second and third mirrors beingarranged so that the radiation contacts the respective concave surfacesof the second and third mirrors, wherein λ is about 800 nm or less.

In general, in a further aspect, the invention features an objectivearranged to image radiation of wavelength λ from an object plane to animage plane. The objective includes a first group of mirrors arranged toimage the radiation from the object plane to a first intermediate-imageplane, the first group of mirrors comprising a first mirror where thefirst mirror does not include an opening for passage of the radiationfrom the object plane to the image plane; and a second group of elementsarranged to image the radiation from the intermediate-image plane to theimage plane, the second group of elements comprising a second mirror,where the second mirror includes a concave surface and is thenext-to-last mirror in a path of the radiation from the object plane tothe image plane and the second mirror is arranged so that the radiationcontacts the concave surface, wherein λ is about 800 nm or less.

In general, in another aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane, the plurality ofelements including a first element that includes an opening for passageof the radiation from the object plane to the image plane; and a stoppositioned between the object plane and the image plane, the stop beingseparate from each of the plurality of elements. The opening in thefirst element results in an obscuration of an aperture of the objectiveat an exit pupil and the stop is configured to reduce variations of theobscuration as a function of a position with respect to the exit pupil,and wherein the objective is a catoptric objective.

In general, in a further aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane; and a stoppositioned substantially at a pupil plane of the objective, the stopbeing configured to substantially block radiation from the object plane,where the stop is separate from each of the plurality of elements. Theobjective is a catoptric objective.

In general, in another aspect, the invention features an objectivearranged to image radiation from an object plane to an image plane. Theobjective includes a plurality of elements arranged to direct theradiation from the object plane to the image plane where, for ameridional section of the objective, the radiation has a maximum angleof incidence on the elements of less than 20°. The objective has animage side numerical aperture of about 0.4 or more and the objective isa catoptric objective.

Embodiments of the objectives may include one or more of the followingfeatures.

In some embodiments, the plurality of elements includes no more than sixelements (e.g., five element, four elements, three elements, twoelements, one element). Alternatively, in certain embodiments, theplurality of elements includes more than six elements (e.g., sevenelements, eight elements, nine elements, 10 elements, 11 elements, 12elements, 13 elements, 14 elements, 15 elements, 16 elements).

The plurality of elements can include at least one element that has anopening for passage of the radiation from the object plane to the imageplane. The objective can have a field independent obscuration related tothe opening that is less than about 40% (e.g., about 35% or less, about30% or less, about 25% or less, about 20% or less, about 15% or less) ofan aperture radius at a pupil plane of the objective. The plurality ofelements can include two elements that have an opening for passage ofthe radiation from the object plane to the image plane. The plurality ofelements can include at least one element that does not have an opening.In some embodiments, the plurality of elements includes six elementsthat do not have an opening.

The plurality of elements can include at least one element that has aconcave surface, where the element is arranged so that the radiationcontacts the concave surface. In certain embodiments, the plurality ofelements includes four elements that each have a concave surface, wherethe four elements are arranged so that the radiation contacts eachelement's concave surface.

The plurality of elements can include at least one element that has aconvex surface, where the element is arranged so that the radiationcontacts the convex surface. In some embodiments, the plurality ofelements includes four elements that each have a convex surface, wherethe four elements are arranged so that the radiation contacts eachelement's convex surface.

The plurality of elements can include a first group of elements and asecond group of elements, the first group of elements being arranged toimage the radiation from the object plane to a first intermediate-imageplane, and the second group of elements being arranged to image theradiation from the intermediate-image plane to the image plane. In someembodiments, none of the elements in the first group of elementsincludes an opening. In certain embodiments, at least one of theelements in the second group of elements includes an opening for passageof the radiation from the object plane to the image plane. The secondgroup of elements can include a first sub-group of elements and secondsub-group of elements, the first sub-group of elements being arranged toimage the radiation from the first intermediate-image plane to a secondintermediate-image plane, and the second sub-group of elements beingarranged to image the radiation from the second intermediate-image planeto the image plane.

The objective defines an optical axis and at least one of the elementscan be rotationally symmetric with respect to the optical axis. In someembodiments, at least one of the elements is not rotationally symmetricwith respect to the optical axis. The at least one element that is notrotationally symmetric with respect to the optical axis can correspondto a portion of a element that is rotationally symmetric about an axis.

The plurality of elements can include at least one aspherical element.In embodiments, each of the elements in the plurality of elements is anaspherical element.

For a meridional section of the objective, the radiation can have amaximum angle of incidence on a surface of each of the elements of about20° or less (e.g., about 18° or less, about 17° or less, about 15° orless, about 12° or less, about 10° or less).

For a meridional section of the objective, the radiation can have amaximum range of incident angles on a surface of each of the elements ofabout 20° or less (e.g., about 18° or less, about 17° or less, about 15°or less, about 12° or less, about 10° or less, about 8° or less).

The objective can further include an aperture stop positionedsubstantially at a pupil plane of the objective. The objective caninclude a stop element positioned substantially at a pupil plane of theobjective and the objective defines an optical axis that intersects thestop element. The stop element can obscure about 40% or less (e.g.,about 35% or less, about 30% or less, about 25% or less, about 20% orless, about 15% or less) of an aperture radius at the pupil plane. Thestop element can be a portion of one of the plurality of elements. Insome embodiments, the stop element is remote from each of the pluralityof elements. The stop element can reflect substantially no radiationdirected by the elements from the object plane incident on the stopelement. For example, the stop element can reflect about 5% or less(e.g., about 4% or less, about 3% or less, about 2% or less, about 1% orless, about 0.5% or less, 0.1% or less, 0.05% or less, 0.01% or less) ofthe radiation at 1 normally incident on the stop element. The stopelement can include a substrate and a film on the substrate, the filmbeing an anti-reflection film for radiation at λ.

The objective can image the radiation to at least one (e.g., two, three,four or more) intermediate-image plane in addition to the image plane.

A distance from the object plane to the image plane can be about 2,000mm or less (e.g., about 1,800 mm or less, about 1,600 mm or less).

The radiation can have a wavelength λ of about 200 nm or less (e.g.,about 100 nm or less). In some embodiments, λ is in a range from about10 nm to about 20 nm.

The objective can have a maximum image side field dimension of about 5mm or more (e.g., about 10 mm or more, about 12 mm or more).

The objective can have a maximum image side field radius of about 20 mmor less (e.g., about 15 mm or less, about 12 mm or less).

The objective can have a demagnification of about 8× or less (e.g.,about 6× or less, about 4× or less).

The objective can have an image resolution of about 32 nm or less (e.g.,about 25 nm or less, about 18 nm or less).

The objective can have an image-side root-mean-square wavefront error ofabout 0.1λ or less (e.g., about 0.07 λ or less, about 0.03 λ or less),where λ is a wavelength of the radiation.

The objective can be telecentric with respect to the image plane.

A minimum distance between a surface of the elements and the image planecan be about 20 mm or more (e.g., about 25 mm or more, about 30 mm ormore, about 35 mm or more).

Each element in the projection objective can reflect about 50% or more(e.g., about 60% or more, about 70% or more) of the radiation normallyincident on a surface of the element.

At least some of the elements can include a plurality of layers of atleast two different materials, wherein a thickness of each of the layersis about λ or less, where λ is a wavelength of the radiation. In someembodiments, one of the different materials includes silicon and anotherof the different materials comprises molybdenum. The thickness of eachof the layers can be about λ/4. The plurality of layers can includeabout 20 or more layers.

In embodiments that include a stop (e.g., an obscuration stop), anoptical axis of the objective can intersect the stop. The plurality ofelements can include a first element and a second element and the stopcan be positioned to block some of the radiation directed from the firstelement to the second element. The plurality of elements can include afirst element, where the first element includes an opening for passageof the radiation from the object plane to the image plane. The stop canhave a dimension corresponding to about 40% or less (e.g., about 30% orless) of a diameter of an aperture of the objective at the pupil plane.

In certain aspects, the invention features a lithography tool that caninclude any of the foregoing objectives.

Embodiments of the foregoing objectives can include any of the followingadvantages. For example, embodiments can include catoptric projectionobjectives that have a high image-side numerical aperture. A highimage-side numerical aperture can provide high image resolution.

The projection objectives can have a high image-side numerical apertureand relatively little angular variation in the angle of incidence ofrays on the reflective elements forming the projection objective.Accordingly, variations in the intensity of radiation reflected from thereflective elements can be reduced relative to projection objectiveswhere radiation is incident on one or more reflective elements over alarge range of incident angles. Reduced intensity variations can providebetter image quality.

Projection objectives can have a high image-side numerical aperture anda relatively large image side working distance, providing sufficientspace for accessing the image plane. For example, projection objectivescan have an image-side working distance of about 15 mm or more.

In some embodiments, projection objectives are telecentric at the imageplane. This can provide for constant or nearly constant imagemagnification over a range of image-side working distances.

In embodiments, projection objectives can include mirrors havingopenings for the passage of radiation, but with relatively lowobscuration of the pupil. Low obscuration can provide better imagequality.

In certain embodiments, projection objectives have extremely highresolution. For example, projection objectives can have the capabilityof resolving structures smaller than about 50 nm. High resolution can beachieved in projection objectives that have a high image-side numericalaperture that are designed for operation at short wavelengths (e.g.,about 10 nm to about 30 nm).

Projection objectives can provide images with low aberrations. Incertain embodiments, projection objectives are corrected for wavefronterror of about 10 mλ or less. In certain embodiments, projectionobjectives are corrected for distortion below values of about 1 nm.

Projection objectives can include one or more pupil planes that areaccessible for positioning an aperture stop or an obscuration stop atthe pupil plane.

Embodiments of projection objectives can be adapted for operation at avariety of different wavelengths, including visible and ultraviolet (UV)wavelengths. Embodiments can be adapted for operation at Extreme UV(EUV) wavelengths. Furthermore, embodiments can be adapted for use atmore than one wavelength, or over a range of wavelengths.

In certain embodiments, projection objectives have relatively low rayangles at the reticle and have a relatively high image-side numericalaperture. For example, radiation from the illumination system can beincident on the reticle at angles of about 10° or less (e.g., about 7°)with respect to the optical axis, while the projection objective has animage-side numerical aperture of about 0.4 or more.

In certain embodiments, projection objective can include features thatallow a reduction in the complexity of the illumination system. Forexample, the location of the entrance pupil of projection objectives maybe in front of the object plane. In other words, chief rays starting atdifferent field points are divergent with respect to each other and withrespect to the optical axis. This can make the entrance pupil of theprojection objective/exit pupil of the illumination system accessiblewithout using a telescope in the illumination system to relay theillumination system's exit pupil to the location of the projectionobjective's entrance pupil.

In certain embodiments, the projection objective can include arelatively large working space close to the position where the opticalaxis intersects the object plane. This can allow convenient placement ofcomponents (e.g., components of the illumination system) close to thereticle. In some embodiments, this can be achieved by designing theprojection objective so that the mirror physically closest to the objectplane is positioned relatively far from the optical axis. In such cases,the bundle of rays that goes from the reticle to the first mirror of theprojection objective can intersect a bundle that goes from the secondmirror of the projection objective to third mirror.

Other features and advantages will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of an embodiment of a microlithography tool.

FIG. 2 is a schematic view showing a portion of the microlithographytool shown in FIG. 1.

FIG. 3 is a cross-sectional view of a portion of a mirror from aprojection objective shown in meridional section.

FIG. 4A is a plan view of an embodiment of a mirror from a projectionobjective that includes an opening.

FIG. 4B is a plan view of an embodiment of a mirror from a projectionobjective that does not include an opening.

FIG. 5A is a cross-sectional view of an embodiment of a partialobjective shown in meridional section.

FIG. 5B is a cross-sectional view of another embodiment of a partialobjective shown in meridional section.

FIG. 6A is a cross-sectional view of another embodiment of a partialobjective shown in meridional section.

FIG. 6B is a cross-sectional view of another embodiment of a partialobjective shown in meridional section.

FIG. 7A is a cross-sectional view of a portion of an embodiment of aprojection objective shown in meridional section, where the projectionobjective includes an obscuration stop on a mirror.

FIG. 7B is a cross-sectional view of a portion of an embodiment of aprojection objective shown in meridional section, where the projectionobjective includes an obscuration stop positioned between two mirrors.

FIG. 7C is a cross-sectional view of a portion of another embodiment ofa projection objective shown in meridional section, where the projectionobjective includes an obscuration stop positioned between two mirrors.

FIG. 7D is a plan view of an obscuration stop mounted in a ring-shapeframe.

FIG. 8 is a plan view of an embodiment of a ring segment field.

FIG. 9A is a cross-sectional view of a portion of the microlithographytool shown in FIG. 1.

FIG. 9B is a cross-sectional view of a portion of an embodiment of aprojection objective shown in meridional section.

FIG. 10 is a cross-sectional view of an embodiment of a projectionobjective shown in meridional section.

FIG. 11 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 12 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 13 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 14 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 15A is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 15B is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 15C is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 15D is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 15E is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 16 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 17 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 18 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 19 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 20 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 21 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 22 is a cross-sectional view of a portion of a projection objectiveshown in meridional section.

FIG. 23 is a cross-sectional view of a portion of a projection objectiveshown in meridional section.

FIG. 24 is a cross-sectional view of a portion of a projection objectiveshown in meridional section.

FIG. 25 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 26 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 27 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 28 is a cross-sectional view of a further embodiment of aprojection objective and an illumination system, shown in meridionalsection.

FIG. 29 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 30 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 31 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

FIG. 32 is a cross-sectional view of a further embodiment of aprojection objective shown in meridional section.

FIG. 33 is a cross-sectional view of another embodiment of a projectionobjective shown in meridional section.

DETAILED DESCRIPTION

In general, the disclosure relates to catoptric projection objectivesthat have a relatively high numerical aperture. Catoptric projectionobjectives with relatively high numerical apertures can be used inmicrolithography tools. Referring to FIG. 1, a microlithography tool 100generally includes a light source 110, an illumination system 120, aprojection objective 101, and a stage 130. A Cartesian co-ordinatesystem is shown for reference. Light source 110 produces radiation at awavelength λ and directs a beam 112 of the radiation to illuminationsystem 120. Illumination system 120 interacts with (e.g., expands andhomogenizes) the radiation and directs a beam 122 of the radiation to areticle 140 positioned at an object plane 103. Projection objective 101images radiation 142 reflected from reticle 140 onto a surface of asubstrate 150 positioned at an image plane 102. The radiation on theimage-side of projection objective 101 is depicted as rays 152.Substrate 150 is supported by stage 130, which moves substrate 150relative to projection objective 101 so that projection objective 101images reticle 140 to different portions of substrate 150.

Projection objective 101 includes an optical axis 105. As depicted inFIG. 1, projection objective 101 images a portion of reticle 140 that isnot coincident with optical axis 105 to image plane 102.

Light source 110 is selected to provide radiation at a desiredoperational wavelength, λ, of tool 100. In some embodiments, lightsource 110 is a laser light source, such as a KrF laser (e.g., having awavelength of about 248 nm) or an ArF laser (e.g., having a wavelengthof about 193 nm). Non-laser light sources that can be used includelight-emitting diodes (LEDs), such as LEDs that emit radiation in theblue or UV portions of the electromagnetic spectrum, e.g., about 365 nm,about 280 nm or about 227 nm.

Typically, for projection objectives designed for operation inlithography tools, wavelength λ is in the ultraviolet portion of theelectromagnetic spectrum. For example, λ can be about 400 nm or less(e.g., about 300 nm or less, about 200 nm or less, about 100 nm or less,about 50 nm or less, about 30 nm or less). λ can be more than about 2 nm(e.g., about 5 nm or more, about 10 nm or more). In embodiments, λ canbe about 193 nm, about 157 nm, about 13 nm, or about 11 nm. Using arelatively short wavelength may be desirable because, in general, theresolution of a projection objective is approximately proportional tothe wavelength. Therefore shorter wavelengths can allow a projectionobjective to resolve smaller features in an image than equivalentprojection objectives that use longer wavelengths. In certainembodiments, however, λ can be in non-UV portions of the electromagneticspectrum (e.g., the visible portion).

In general, radiation from light source 110 can be substantiallymonochromatic or can include radiation at a number of differentwavelengths. In some embodiments, projection objective 101 can bedesigned for operation at a single wavelength or at multiplewavelengths. In some embodiments, projection objectives can be designedfor operation at multiple wavelengths, such as over bands of wavelengths(e.g., from about 10 nm to about 30 nm, from about 200 nm to about 400nm, from about 400 nm to about 700 nm). Illumination system 120 includesoptical components arranged to form a collimated radiation beam with ahomogeneous intensity profile. Illumination system 120 typically alsoincludes beam steering optics to direct beam 122 to reticle 140. In someembodiments, illumination system 120 also include components to providea desired polarization profile for the radiation beam.

Image plane 103 is separated from object plane 102 by a distance L,which is also referred to as the lengthwise dimension of projectionobjective 101. In general, this distance depends on the specific designof projection objective 101 and the wavelength of operation of tool 100.In some embodiments, such as in tools designed for EUV lithography, L isin a range from about 1 m to about 3 m (e.g., in a range from about 1.5m to about 2.5 m). In certain embodiments, L is less than 2 m, such asabout 1.9 m or less (e.g., about 1.8 m or less, about 1.7 m or less,about 1.6 m or less, about 1.5 m or less). L can be more than about 0.2m or more (e.g., about 0.3 m or more, about 0.4 m or more, about 0.5 mor more, about 0.6 m or more, about 0.7 m or more, about 0.8 m or more,about 0.9 m or more, about 1 m or more).

Projection objective 101 has a magnification ratio, which refers to theratio of the dimensions of the field at object plane 103 to thecorresponding dimensions of the field at image plane 102. Typically,projection objectives used in lithography tools are reduction projectionobjectives, meaning they reduce the dimensions of, or demagnify, theimage. In some embodiments, therefore, projection objective 101 canproduce a field at image plane 102 whose dimensions are reduced by about2× or more (e.g., about 3× or more, about 4× or more, about 5× or more,about 6× or more, about 7× or more, about 8× or more, about 9× or more,about 10× or more) compared to the dimensions at object plane 103. Inother words, projection objective 101 can have a demagnification ofabout 2× or more, (e.g., about 3× or more, about 4× or more, about 5× ormore, about 6× or more, about 7× or more, about 8× or more, about 9× ormore, about 10× or more). More generally, however, projection objectivescan be designed to provide a magnified image or an image the same sizeas the object.

Referring also to FIG. 2, rays 152 define a cone of light paths thatform the reticle image at image plane 102. The angle of the cone of raysis related to the image-side numerical aperture (NA) of projectionobjective 101. Image-side NA can be expressed asNA=n _(o) sin θ_(max),where n_(o) refers to the refractive index of the immersing mediumadjacent the surface of substrate 150 (e.g., air, nitrogen, water, orevacuated environment), and θ_(max) is the half-angle of the maximumcone of image forming rays from projection objective 101.

In general, projection objective 101 has a relatively high image-sideNA. For example, in some embodiments, projection objective 101 has animage-side NA of more than 0.4 (e.g., about 0.45 or more, about 0.5 ormore, about 0.55 or more, about 0.6 or more, about 0.65 or more, about0.7 or more, about 0.75 or more, about 0.8 or more, about 0.85 or more,about 0.9 or more). In general, the resolution of projection objective101 varies depending on wavelength λ and the image-side NA. Withoutwishing to be bound by theory, the resolution of a projection objectivecan be determined based on the wavelength and image-side NA based on theformula,

${R = {k\frac{\lambda}{NA}}},$where R is the minimum dimension that can be printed and k is adimensionless constant called the process factor. k varies depending onvarious factors associated with the radiation (e.g., the polarizationproperties), the illumination properties (e.g., partial coherence,annular illumination, dipole settings, quadrupole settings, etc.) andthe resist material. Typically, k is in a range from about 0.4 to about0.8, but can also be below 0.4 and higher than 0.8 for certainapplications.

In some embodiments, projection objective 101 has a relatively highresolution (i.e., the value of R can be relatively small). For example,R can be about 150 nm or less (e.g., about 130 nm or less, about 100 nmor less, about 75 nm or less, about 50 nm or less, about 40 nm or less,about 35 nm or less, about 32 nm or less, about 30 nm or less, about 28nm or less, about 25 nm or less, about 22 nm or less, about 20 nm orless, about 18 nm or less, about 17 nm or less, about 16 nm or less,about 15 nm or less, about 14 nm or less, about 13 nm or less, about 12nm or less, about 11 nm or less, such as about 10 nm).

The quality of images formed by projection objective 101 can bequantified in a variety of different ways. For example, images can becharacterized based on the measured or calculated departures of theimage from idealized conditions associated with Gaussian optics. Thesedepartures are generally known as aberrations. One metric used toquantify the deviation of a wavefront from the ideal or desired shape isthe root-mean-square wavefront error (W_(rms)). W_(rms) is defined inthe “Handbook of Optics,” Vol. I, 2^(nd) Ed., edited by Michael Bass(McGraw-Hill, Inc., 1995), at page 35.3, which is incorporated herein byreference. In general, the lower the W_(rms) value for an objective,less the wavefront deviates from its desired or ideal shape, and thebetter the quality of the image. In certain embodiments, projectionobjective 101 can have a relatively small W_(rms) for images at imageplane 102. For example, projection objective 101 can have a W_(rms) ofabout 0.1 λ or less (e.g., about 0.07 λ or less, about 0.06 λ or less,about 0.05 λ or less, about 0.045 λ or less, about 0.04 λ or less, about0.035 λ or less, about 0.03 λ or less, about 0.025 λ or less, about 0.02λ or less, about 0.015 λ or less, about 0.01 λ or less, such as about0.005 λ).

Another metric that can be used to evaluate the quality of the image isreferred to as field curvature. Field curvature refers to thepeak-to-valley distance for the field point dependent position of thefocal plane. In some embodiments, projection objective 101 can have arelatively small field curvature for images at image plane 102. Forexample, projection objective 101 can have an image-side field curvatureof about 20 nm or less (e.g., about 15 nm or less, about 12 nm or less,10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5nm or less, 4 nm or less, 3 nm or less, 2 nm or less, 1 nm or less, suchas about 0.5 nm).

Another metric that can be used to evaluate the optical performance isreferred to as distortion. Distortion refers to the maximum absolutevalue of the field point dependent deviation from the ideal image pointposition in the image plane. In some embodiments, projection objective101 can have a relatively small distortion. For example, projectionobjective 101 can have a distortion of about 50 nm or less, (e.g. about40 nm or less, about 30 nm or less, about 20 nm or less, about 15 nm orless, about 12 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nmor less, such as 1 nm).

Being a catoptric system, projection objective 101 includes a number ofmirrors arranged to direct radiation reflected from reticle 140 tosubstrate 150 in a way that forms an image of reticle 140 on the surfaceof substrate 150. Specific designs of projection objectives aredescribed below. More generally, however, the number, size, andstructure of the mirrors generally depends on the desired opticalproperties of projection objective 101 and the physical constraints oftool 100.

Projection objective 101 is also telecentric with respect to the imageplane. Thus, projection objective 101 can provide substantially constantmagnification over a range of image-size working distances.

In general, the number of mirrors in projection objective 101 may vary.Typically, the number of mirrors is related to various performancetrade-offs associated with the optical performance characteristics ofthe objective, such as the desired throughput (e.g., the intensity ofradiation from the object that forms the image at image plane 102), thedesired image-side NA and related image resolution, and the desiredmaximum pupil obscuration.

In certain embodiments, projection objective 101 has at least fourmirrors (e.g., five or more mirrors, six or more mirrors, seven or moremirrors, eight or more mirrors, nine or more mirrors, ten or moremirrors, eleven or more mirrors, twelve or more mirrors). In embodimentswhere it is desirable that all the mirrors of the objective arepositioned between the object plane and the image plane, objective 101will typically have an even number of mirrors (e.g., four mirrors, sixmirrors, eight mirrors, ten mirrors).

Projection objective 101 generally includes one or more mirrors withpositive optical power. In other words, the reflective portion of themirror has a concave surface and is referred to as a concave mirror.Projection objective 101 can include two or more (e.g., three or more,four or more, five or more, six or more) concave mirrors. Projectionobjective 101 can also include one or more mirrors that have negativeoptical power. This means that one or more of the mirrors has areflective portion with a convex surface (referred to as a convexmirror). In some embodiments, projection objective 101 includes two ormore (e.g., three or more, four or more, five or more, six or more)convex mirrors.

In certain embodiments, the arrangement of mirrors in projectionobjective 101 images radiation from object plane 103 to one or moreintermediate-image planes.

Embodiments that have one or more intermediate images, also include twoor more pupil planes. In some embodiments, at least one of these pupilplanes is physically accessible for the purposes of placing an aperturestop substantially at that pupil plane. An aperture stop is used toreduce the size of the projection objective's aperture.

In general, the mirrors are formed so that they reflect a substantialamount of radiation of wavelength λ normally-incident thereon orincident thereon over a certain range of incident angles. Mirrors can beformed, for example, so that they reflect about 50% or more (e.g., about60% or more, about 70% or more, about 80% or more, about 90% or more,about 95% or more, 98% or more) of normally incident radiation at λ.

In some embodiments, the mirrors include a multilayer stack of films ofdifferent materials arranged to substantially reflect normally incidentradiation at λ. Each film in the stack can have an optical thickness ofabout λ/4. Multilayer stacks can include about 20 or more (e.g., about30 or more, about 40 or more, about 50 or more) films. In general, thematerials used to form the multilayer stacks are selected based onoperational wavelength λ. For example, multiple alternating films ofmolybdenum and silicon or molybdenum and beryllium can be used to formmirrors for reflecting radiation in the 10 nm to 30 nm range (e.g., forλ of about 13 nm or about 11 nm, respectively).

In certain embodiments, the mirrors are made of quartz glass coated witha single layer of aluminum and overcoated with one or more layers ofdielectric materials, such as layers formed from MgF₂, LaF₂, or, Al₂O₃.Mirrors formed from aluminum with dielectric coatings can be used, forexample, for radiation having a wavelength of about 193 nm.

In general, the percentage of radiation at λ reflected by a mirrorvaries as a function of the angle of incidence of the radiation on themirror surface. Because imaged radiation propagates through a catoptricprojection objective along a number of different paths, the angle ofincidence of the radiation on each mirror can vary. This effect isillustrated with reference to FIG. 3, which shows a portion of a mirror300, in meridional section, that includes a concave reflective surface301. Imaged radiation is incident on surface 301 along a number ofdifferent paths, including the paths shown by rays 310, 320, and 330.Rays 310, 320, and 330 are incident on portions of surface 301 where thesurface normal is different. The direction of surface normal at theseportions is shown by lines 311, 321, and 331, corresponding to rays 310,320, and 330, respectively. Rays 310, 320, and 330 are incident onsurface 301 at angles θ₃₁₀, θ₃₂₀, and θ₃₃₀, respectively. In general,angles θ₃₁₀, θ₃₂₀, and θ₃₃₀ may vary.

For each mirror in projection objective 101, the incident angles ofimaged radiation can be characterized in a variety of ways. Onecharacterization is the maximum angle of incidence of rays on eachmirror in a meridional section of projection objective 101. In general,θ_(max) can vary for different mirrors in projection objective 101. Inembodiments, the maximum value of θ_(max) for all the mirrors inprojection objective 101 is about 75° or less (e.g., about 70° or less,about 65° or less, about 60° or less, about 55° or less, about 50° orless, about 45° or less). θ_(max) can be more than about 5° (e.g., about10° or more, about 20° or more). In some embodiments, the maximum valueof θ_(max) can be relatively low. For example, the maximum value ofθ_(max) can be about 40° or less (e.g., about 35° or less, about 30° orless, about 25° or less, about 20° or less, about 15° or less, about 13°or less, about 10° or less).

Another characterization is the angle of incidence of the chief raycorresponding to the central field point on each mirror in a meridionalsection of projection objective 101. This angle is referred to asθ_(CR). In general, θ_(CR) can vary. In some embodiments the maximumvalue of θ_(CR), θ_(CR)(max), in projection objective 101 can berelatively low. For example, θ_(CR)(max) can be about 35° or less (e.g.,about 30° or less, about 25° or less, about 20° or less, about 15° orless, about 13° or less, about 10° or less, about 8° or less, about 5°or less).

Each mirror in projection objective 101 can also be characterized by therange of angles of incidence, Δθ, of rays for a meridional section ofprojection objective 101. For each mirror, Δθ corresponds to thedifference between θ_(max) and θ_(min), where θ_(min) is the minimumangle of incidence of rays on each mirror in a meridional section ofprojection objective 101. In general, Δθ may vary for each mirror inprojection objective 101. For some mirrors, Δθ can be relatively small.For example, Δθ can be about 20° or less (e.g., about 15° or less, about12° or less, about 10° or less, about 8° or less, about 5° or less,about 3° or less, 2° or less). Alternatively, for some mirrors inprojection objective 101, Δθ can be relatively large. For example, Δθfor some mirrors can be about 20° or more (e.g., about 25° or more,about 30° or more, about 35° or more, about 40° or more). In someembodiments, the maximum value for Δθ, Δθ_(max), for all the mirrors inprojection objective 101 can be relatively small. For example, Δθ_(max)can be about 25° or less (e.g., about 20° or less, about 15° or less,about 12° or less, about 10° or less, about 9° or less, about 8° orless, about 7° or less, about 6° or less, about 5° or less, such as 3°).

In general, catoptric projection objectives are designed to account forthe obscuration of ray paths caused by the reflective elements, asopposed to transmissive elements used in a dioptric system. The mirrorsare designed and arranged so that radiation imaged by the projectionobjective follows a path through a transmissive opening (e.g., a hole)in the mirror, or passes the edge of the mirror. Thus, mirrors inprojection objective 101 can be categorized as being in one of twogroups: mirrors in the first group include an opening for the passage ofradiation and mirrors in the second group do not.

An example of a mirror 600 that includes an opening is shown in FIG. 4A.Mirror 600 includes an opening 610. Mirror 600 can be arranged inprojection objective 101 so that optical axis 105 intersects opening610. Mirror 600 is circular in shape with diameter D. Generally, D isselected based on the design of projection objective 101. In someembodiments, D is about 1,500 mm or less (e.g., about 1,400 nm or less,about 1,300 mm or less, about 1,200 mm or less, about 1,100 mm or less,about 1,000 mm or less, about 900 mm or less, about 800 mm or less,about 700 mm or less, about 600 mm or less, about 500 mm or less, about400 mm or less, about 300 mm or less, about 200 mm or less, about 100 mmor less). D may be more than about 10 mm (e.g., about 20 mm or more,about 50 mm or more).

In general, mirrors in projection objective 101 that include an openingcan be circular or non-circular in shape. Examples of non-circularopenings include polygonal openings (e.g., square openings, rectangularopenings, hexagonal openings, octagonal openings, irregular polygonalopenings) and non-circular, curved openings (e.g., elliptical openings,irregular curved openings).

Mirrors that are non-circular in shape can have a maximum dimension thatis about 1,500 mm or less (e.g., about 1,400 nm or less, about 1,300 mmor less, about 1,200 mm or less, about 1,100 mm or less, about 1,000 mmor less, about 900 mm or less, about 800 mm or less, about 700 mm orless, about 600 mm or less, about 500 mm or less, about 400 mm or less,about 300 mm or less, about 200 mm or less, about 100 mm or less.)Non-circular mirrors may have a maximum dimension that is more thanabout 10 mm (e.g., about 20 mm or more, about 50 mm or more).

Opening 610 is circular in shape with diameter D_(o). D_(o) depends onthe design of projection objective 101 and is generally sized to allow asufficiently large opening for the passage of radiation from objectplane 103 to image plane 102.

In general, mirror openings can be circular or non-circular in shape.Examples of non-circular openings include polygonal openings (e.g.,square openings, rectangular openings, hexagonal openings, octagonalopenings) and non-circular, curved openings (e.g., elliptical openings,irregular curved openings).

Openings that are non-circular in shape can have a maximum dimensionthat is about 0.75 D or less (e.g., about 0.5 D or less, about 0.4 D orless, about 0.3 D or less, about 0.2 D or less, about 0.1 D or less,about 0.05 D or less). The maximum opening of a non-circular opening canbe more than about 0.01 D (e.g., about 0.02 D or more, about 0.03 D ormore, about 0.04 D or more, about 0.05 D or more). In some embodiments,a mirror includes a non-circular opening that has a maximum dimension ofabout 50 mm or less (e.g., about 45 mm or less, about 40 mm or less,about 35 mm or less, about 30 mm or less, about 25 mm or less, about 20mm or less, about 15 mm or less, about 10 mm or less, such as about 5mm).

In embodiments where projection objective 101 includes more than onemirror with an opening, the openings in different mirrors can have thesame shape or can have different shapes. Furthermore, the openings indifferent mirrors can have the same maximum dimension or can havedifferent maximum dimensions.

An example of a mirror 660 that does not include an opening is shown inFIG. 4B. Mirror 660 is in the shape of a ring segment. Mirror 660corresponds to a segment of a circular mirror 670 of diameter D. Mirror660 has a maximum dimension in the x-direction given by M_(x). Inembodiments, M_(x) can be about 1,500 mm or less (e.g., about 1,400 nmor less, about 1,300 mm or less, about 1,200 mm or less, about 1,100 mmor less, about 1,000 mm or less, about 900 mm or less, about 800 mm orless, about 700 mm or less, about 600 mm or less, about 500 mm or less,about 400 mm or less, about 300 mm or less, about 200 mm or less, about100 mm or less). M_(x) can be more than about 10 mm (e.g., about 20 mmor more, about 50 mm or more).

Mirror 660 is symmetric with respect to meridian 675. Mirror 660 has adimension M_(y) along meridian 675. M_(y) can be smaller or larger thanM. In some embodiments, M_(y) is in a range from about 0.1 M_(x) toabout M_(x) (e.g., about 0.2 M_(x) or more, about 0.3 M_(x) or more,about 0.4 M_(x) or more, about 0.5 M_(x) or more, about 0.6 M_(x) ormore, about 0.7 M_(x) or more about 0.8 M_(x) or more, about 0.9 M_(x)or more). Alternatively, in certain embodiments, M_(y) can be about 1.1M_(x) or more (e.g., about 1.5 M_(x) or more), such as in a range fromabout 2 M_(x) to about 10 M. M_(y) can be about 1,000 mm or less (e.g.,about 900 mm or less, about 800 mm or less, about 700 mm or less, about600 mm or less, about 500 mm or less, about 400 mm or less, about 300 mmor less, about 200 mm or less, about 100 mm or less). M_(y) can be morethan about 10 mm (e.g., about 20 mm or more, about 50 mm or more).

Mirrors that do not include an opening may be arranged so that opticalaxis 105 intersects the mirror, or does not intersect the mirror.

In general, projection objective 101 can include mirrors of varyingshape and size, depending on its design. In some embodiments, themaximum dimension of any mirror in projection objective is about 1,500mm or less (e.g., about 1,400 nm or less, about 1,300 mm or less, about1,200 mm or less, about 1,100 mm or less, about 1,000 mm or less, about900 mm or less, about 800 mm or less, about 700 mm or less, about 600 mmor less, about 500 mm or less, such as about 300 mm). In certainembodiments, the maximum dimension of any mirror in projection objectiveis about 10 mm or more (e.g., about 20 mm or more, about 30 mm or more,about 40 mm or more, about 50 mm or more, about 75 mm or more, about 100mm or more).

In certain embodiments, projection objective 101 includes a group ofmirrors (e.g., two or more mirrors, three or more mirrors, four or more,mirrors, five or more mirrors, six or more mirrors) that do not includean opening that are arranged to form an image (e.g., at image plane 102or at some intermediate-image plane). In embodiments where projectionobjective 101 includes additional mirrors to the group of mirrors, thegroup of mirrors is referred to as a partial objective.

In embodiments, projection objective 101 can include more than onepartial objective. For example, projection objective can include twopartial objectives, three partial objectives, four partial objectives,or more than four partial objectives.

An example of a partial objective is partial objective 400 shown in FIG.5A. Partial objective 400 includes mirrors 410, 420, 430, and 440arranged to image radiation from an object plane 403 (e.g.,corresponding to object plane 103 or to an intermediate image plane) toan image plane 402 (e.g., corresponding to image plane 102 or to anintermediate-image plane). The reflective surfaces of mirrors 410, 420,430, and 440 all correspond to portions of axially-symmetric surfaces,where the rest of the mirror surface has been removed to provide a pathfor the imaged radiation. The first mirror in the path of the radiation,mirror 420, is closest to plane 402, while the second mirror in the pathof the radiation, mirror 410, is closest to plane 403.

As another example, referring to FIG. 5B, a partial objective 450includes mirrors 460, 470, 480, and 490 arranged to image radiation froman object plane 453 (e.g., corresponding to object plane 103 or to anintermediate image plane) to an image plane 452 (e.g., corresponding toimage plane 102 or to an intermediate-image plane). Like the mirrorsforming partial objective 400, the reflective surfaces of mirrors 460,470, 480, and 490 all correspond to portions of axially-symmetricsurfaces, where the rest of the mirror surface has been removed toprovide a path for the imaged radiation. The third mirror in the path ofthe radiation, mirror 480, is closest to plane 452, while the secondmirror in the path of the radiation, mirror 460, is closest to plane403.

While partial objectives 400 and 450 are formed from mirrors that do notinclude openings, partial objectives can also be formed from mirrorsthat do include an opening. For example, referring to FIG. 6A, a partialobjective 500 is formed from mirrors 510 and 520, where mirror 510includes an opening 511. Partial objective 500 is arranged to imageradiation to an image plane 502 (e.g., corresponding to image plane 102or to an intermediate-image plane)).

Referring to FIG. 6B, another example of a partial objective that isformed from mirrors that include an opening is partial objective 550.Partial objective 550 includes mirrors 560 and 570. Mirror 560 includesan opening 561 and mirror 570 includes an opening 571. Partial objective550 is arranged to image radiation to an image plane 552 (e.g.,corresponding to image plane 102 or to an intermediate-image plane)).

Partial objectives that use mirrors that have an opening result in partof a pupil of the partial objective being obscured. Accordingly, inembodiments, projection objective 101 can have an obscured pupil. Theextent to which the exit pupil of projection objective 101 is obscuredcan be characterized by a value, R_(obs), referred to as the obscurationradius, which is the minimum percentage of the aperture radius ofprojection objective 101 that can be obscured at a pupil plane where theobscuration is substantially independent of the field position, asdetermined for a meridional section of projection objective 101. Inother words, the obscuration radius corresponds to the minimumobscuration at a pupil plane that appears substantially the same at allpositions in the field. Due to the rotational symmetry of the systemwith respect to optical axis it is sufficient to calculate theobscuration radius in the meridional section. In some embodiments thatinclude one or more mirrors with an opening, projection objection 101can have relatively little pupil obscuration. For example, R_(obs) canbe about 30% or less (e.g., about 25% or less, about 22% or less, about20% or less, about 18% or less, about 15% or less, about 12% or less,about 10% or less). In certain embodiments, R_(obs) is more than about2% (e.g., about 5% or more, about 8% or more).

In some embodiments, projection objective 101 includes one or more pupilplanes that are physically accessible for positioning a radiationobscuring element (referred to as an obscuration stop). The obscurationstop can be positioned substantially at that pupil plane where the pupilplane intersects optical axis 105. An obscuration stop located in apupil position can result in a field independent obscuration of thepupil in embodiments where projection objective includes one or moremirrors that include openings for the passage of radiation.

Typically, the obscuration stop should be formed from or coated with amaterial that does not reflect radiation at λ (e.g., the material cansubstantially absorb incident radiation at λ) Preferably, theobscuration stop should not result in substantial stray radiation in thesystem.

Referring to FIG. 7A, in some embodiments, a mirror 910 is positionedsubstantially at a pupil plane in projection objective 101 and anobscuration stop 912 is provided on the mirror surface. Obscuration stop912 may be, for example, an antireflective coating for radiation ofwavelength λ. Obscuration stop 912 blocks some incident radiationpropagating along certain ray paths. This is illustrated in FIG. 7A byrays 921, 922, and 923. Rays 921 and 923 intersect the reflectiveportion of mirror 910, while ray 922 intersects obscuration stop 912.Accordingly, radiation propagating along the path of rays 921 and 923 isreflected by mirror 920 towards a downstream mirror 920. Radiationpropagating along the path of ray 922, on the other hand, is blocked byobscuration stop 912.

In certain embodiments, an obscuration stop may be positioned betweenmirrors in projection objective 101. For example, an obscuration stopmay be positioned at a pupil plane that is not coincident with anymirrors in the projection objective. Referring to FIG. 7B, anobscuration stop 926 may be positioned between mirrors 910 and 920 toblock radiation propagating along certain ray paths between the mirrors.Obscuration stop is mounted in place using a support beam 928 that ispassed through an opening 924 in mirror 910.

An alternative mounting scheme is shown in FIGS. 7C and 7D, where anobscuration stop 930 is positioned between mirrors 910 and 920 by amounting ring 932 that has an inner diameter larger than the projectionobjective aperture at the pupil plane where obscuration stop 930 ispositioned. Obscuration stop 930 is affixed to ring-shaped frame 932 bythree radial beams 934. Beams 934 are made sufficiently narrow so as notto substantially block radiation.

In certain embodiments, an obscuration stop positioned substantially ata pupil plane may be removed or exchanged for another obscuration stopwithout having to remove or exchange a mirror in the projectionobjective.

In some embodiments, an obscuration stop can be mounted on atransmissive optical element. For example, in embodiments where thereexist materials that are substantially transmissive at the system'soperating wavelength λ, and these materials have sufficient mechanicalstrength to support an obscuration stop, an obscuration stop can bemounted on a transmissive flat element. As an example, in embodimentswhere λ is in the visible portion of the electromagnetic spectrum, anobscuration stop can be mounted by coating or affixing the obscurationstop onto a flat glass element of sufficient size that can be mounted tothe frame of projection objective 101.

Typically, obscuration stops are used in embodiments where at least oneof the mirrors in the projection objective 101 has an opening for thepassage of radiation. In general, the size of the obscuration stop canvary. In certain embodiments, the obscuration stop is the smallest sizepossible that provides a substantially field independent obscuration atthe exit pupil of the projection objective. In some embodiments, theobscuration stop can have a radial dimension that is about 60% or less(e.g., about 55% or less, about 50% or less, about 45% or less, about40% or less, about 35% or less, about 30% or less, about 25% or less,about 20% or less) of the radius of the pupil aperture.

In general, the shape of the field of projection objective 101 can vary.In some embodiments, the field has an arcuate shape, such as the shapeof a segment of a ring. For example, projection objectives that includepartial objectives formed from mirrors without openings, such as partialobjectives 400 and 450 described above, can have field in the shape of aring segment. Referring to FIG. 8, a ring-segment field 700 can becharacterized by an x-dimension, d_(x), a y-dimension, d_(y), and aradial dimension, d_(r). d_(x) and d_(y) correspond to the dimension ofthe field along the x-direction and y-direction, respectively. d_(r)corresponds to the ring radius, as measured from optical axis 105 to theinner boundary of field 700. Ring-segment field 700 is symmetric withrespect to a plane parallel to the y-z plane and indicated by line 710.In general, the sizes of d_(x), d_(y), and d_(r) vary depending on thedesign of projection objective 101. Typically d_(x) is larger thand_(y). The relative sizes of field dimensions d_(x), d_(y), and d_(r) atobject plane 103 and image plane 102 vary depending on the magnificationor demagnification of projection objective 101.

In some embodiments, d_(x) is relatively large at image plane 102. Forexample, d_(x) at image plane 102 can be more than 1 mm (e.g., about 3mm or more, about 4 mm or more, about 5 mm or more, about 6 mm or more,about 7 mm or more, about 8 mm or more, about 9 mm or more, about 10 mmor more, about 11 mm or more, about 12 mm or more, about 13 mm or more,about 14 mm or more, about 15 mm or more, about 18 mm or more, about 20mm or more, about 25 mm or more). d_(x) can be about 100 mm or less(e.g., about 50 mm or less, about 30 mm or less).

d_(y) at image plane 102 can be in a range from about 0.5 mm to about 5mm (e.g., about 1 mm, about 2 mm, about 3 mm, about 4 mm).

Typically, d_(r) at image plane 102 is in a range from about 10 mm toabout 50 mm. d_(r) can be, for example, about 15 mm or more (e.g., about20 mm or more, about 25 mm or more, about 30 mm or more) at image plane102.

More generally, for other field shapes, projection objective 101 canhave a maximum field dimension of more than 1 mm (e.g., about 3 mm ormore, about 4 mm or more, about 5 mm or more, about 6 mm or more, about7 mm or more, about 8 mm or more, about 9 mm or more, about 10 mm ormore, about 11 mm or more, about 12 mm or more, about 13 mm or more,about 14 mm or more, about 15 mm or more, about 18 mm or more, about 20mm or more, about 25 mm or more) at image plane 102. In certainembodiments, projection objective has a maximum field dimension of nomore than about 100 mm (e.g., about 50 mm or less, about 30 mm or less).

Embodiments of projection objective 101 can have a relatively largeimage-side free working distance. The image-side free working distancerefers to the shortest distance between image plane 102 and the mirrorsurface of the mirror closest to image plane 102. This is illustrated inFIG. 9A, which shows a mirror 810 as the closest mirror to image plane102. Radiation reflects from surface 811 of mirror 810. The image-sidefree working distance is denoted d_(w). In some embodiments, d_(w) isabout 25 mm or more (e.g., about 30 mm or more, about 35 mm or more,about 40 mm or more, about 45 mm or more, about 50 mm or more about 55mm or more, about 60 mm or more, about 65 mm or more). In certainembodiments, d_(w) is about 200 mm or less (e.g., about 150 mm or less,about 100 mm or less, about 50 mm or less). A relatively large workingdistance may be desirable because it can allow the surface of substrate150 to be positioned at image plane 102 without contacting the side ofmirror 810 facing image plane 102.

Analogously, the object-side free working distance refers to theshortest distance between object plane 103 and the surface of thereflective side of the mirror in projection objective 101 closest toobject plane 103. In some embodiments, projection objective 101 has arelatively large object-side free working distance. For example,projection objective 101 can have an object-side free working distanceof about 50 mm or more (e.g., about 100 mm or more, about 150 mm ormore, about 200 mm or more, about 250 mm or more, about 300 mm or more,about 350 mm or more, about 400 mm or more, about 450 mm or more, about500 mm or more, about 550 mm or more, about 600 mm or more, about 650 mmor more, about 700 mm or more, about 750 mm or more, about 800 mm ormore, about 850 mm or more, about 900 mm or more, about 950 mm or more,about 1,000 mm or more). In certain embodiments, the object-side freeworking distance is no more than about 2,000 mm (e.g., about 1,500 mm orless, about 1,200 mm or less, about 1,000 mm or less). A relativelylarge object-side free working distance may be advantageous inembodiments where access to the space between projection objective 101and object plane 103 is desired. For example, in embodiments wherereticle 140 is a reflective reticle, it is necessary to illuminate thereticle from the side that faces objective 101. Therefore, there shouldbe sufficient space between projection objective 101 and object plane103 to allow the reticle to be illuminated by illumination system 120 ata desired illumination angle. Furthermore, in general, a largerobject-side free working distance allows flexibility in design of therest of tool, for example, by providing sufficient space to mount othercomponents between projection objective 101 and the support structurefor reticle 140.

In some embodiments, the mirror that is closest to object plane 103 canpositioned away from optical axis 105. In other words, optical axis 105does not intersect the mirror closest to object plane 103. For example,referring to FIG. 9B, in certain embodiments, projection objective 101includes four mirrors 941-944, where mirror 941 is the closest mirror toobject plane 103. The minimum distance between mirror 941 and opticalaxis 105 is shown by distance 946.

In some embodiments, distance 946 can be about 50 mm or more (e.g.,about 60 mm or more, about 70 mm or more, about 80 mm or more, about 90mm or more, about 100 mm or more, about 110 mm or more, about 120 mm ormore, about 130 mm or more, about 140 mm or more, about 150 mm or more,about 160 mm or more, about 170 mm or more, about 180 mm or more, about190 mm or more, about 200 mm or more, about 210 mm or more, about 220 mmor more, about 230 mm or more, about 240 mm or more, about 250 mm ormore, about 260 mm or more, about 270 mm or more, about 280 mm or more,about 290 mm or more, about 300 mm or more). In certain embodiments,distance 946 is no more than about 1,000 mm (e.g., about 500 mm orless).

It may be advantageous to have a relatively large distance 946, becauseit can provide a relatively large space close to the point where opticalaxis 105 intersects object plane 103. This space may be utilized byother components in the lithography tool, such as one or more opticalcomponents of the illumination system (e.g., a grazing incidencereflective element).

Some of the radiation imaged by the projection objective follows thepath of ray 947. The ray intersect the mirrors in the following order:mirror 942; mirror 941; mirror 943; and mirror 944. The path of ray 947crosses itself at position 945, after reflecting from mirror 941, andbetween mirrors 941 and 943.

In general, projection objective 101 can be designed so that chief raysfrom reticle 140 either converge to, diverge from, or are parallel tooptical axis 105. In other words, the position of the entrance pupil ofprojection objective 101 can vary with respect to object plane 103depending on the projection objective design. In some embodiments, forexample, object plane 103 is between projection objective 101 and theentrance pupil of projection objective 101. Alternatively, in certainembodiments, the entrance pupil is positioned between object plane 103and projection objective 101.

Illumination system 120 may be arranged so that the exit pupil of theillumination system is positioned substantially at the entrance pupil ofprojection objective 101. In certain embodiments, illumination system120 includes a telescope subsystem which projects the illuminationsystem's exit pupil to the location of the entrance pupil of projectionobjective 101. However, in some embodiments, the exit pupil ofillumination system 120 is positioned at the entrance pupil ofprojection objective 101 without using a telescope in the illuminationsystem. For example, when the object plane 103 is between projectionobjective 101 and the entrance pupil of the projection objective, theexit pupil of illumination system 120 may coincide with the projectionobjective's entrance pupil without using a telescope in the illuminationsystem.

In general, projection objective 101 can be designed using commerciallyavailable optical design software like ZEMAX, OSLO, or Code V.Typically, a design is started by specifying an initial projectionobjective design (e.g., arrangement of mirrors) along with parameterssuch as the radiation wavelength, field size and numerical aperture, forexample. The code then optimizes the design for specified opticalperformance criteria, such as, for example, wavefront error, distortion,telecentricity, and image uniformity.

Referring to FIG. 10, an embodiment of a projection objective 1000includes eight mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2, and has animage-side numerical aperture of 0.54 and an operating wavelength of13.4 nm. Mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2 are all asphericalmirrors. Projection objective 1000 images radiation from object plane103 to image plane 102 with a demagnification ratio of 6× and aresolution of about 15 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,745 mm.

Projection objective 1000 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 20 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.024λ. Image-side field curvature is 3 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S1 is a concavemirror; mirror S2 is a convex mirror; mirror S5 is a convex mirror;mirror S6 is a concave mirror; mirror S3 is a convex mirror; mirror S4is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror.

Mirrors S3, S4, SK1, and SK2 include openings. Opening A1 is located inmirror S3, opening A2 is located in mirror SK2, opening A3 is located inmirror SK1, and opening A4 is located in mirror S4. Mirrors S1, S2, S5,and S6 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 43% of the aperture radius.

The image-side free working distance, shown as distance A between thevertex V3, i.e., the vertex of primary concave mirror SK1, and imageplane 102 is 40 mm. The object-side free working distance is 100 mm.

The maximum angle of incidence on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 of a chief ray of a central field point is 33.8°. The maximumangle of incidence of any ray on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 is 38.6°. The maximum range of incident angles on any of mirrorsS1, S2, S3, S4, S5, S6, SK1, and SK2 is 12.0°.

The size of the largest mirror in meridional section is 669 mm. The sizeof the largest mirror in the x-direction is 675 mm.

The mirrors are arranged so that projection objective 1000 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1000 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop. At least one of the pupil planes isaccessible for positioning an obscuration stop, at the position ofmirror S3, for example.

First partial objective 1010 has a total of four mirrors: mirror S1,mirror S2, mirror S5, and mirror S6. First partial objective 1010 formsan intermediate image Z1 in or close to mirror S4. This image isdemagnified 1.77×.

Second partial objective 1020 has a total of two mirrors: mirror S3, andmirror S4. Second partial objective 1020 forms an intermediate image Z2in or close to mirror S3. This image is demagnified 1.18×.

Third partial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image in or close toimage plane 102. This image is demagnified 2.88×.

An aperture stop B is positioned near mirror S5.

Data for projection objective 1000 is presented in Table 1A and Table 1Bbelow. Table 1A presents optical data, while Table 1B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 1A and Table 1B, the mirror designations correlate as follows:mirror 1 corresponds to mirror S1; mirror 2 corresponds to mirror S2;mirror 3 corresponds to mirror S5; mirror 4 corresponds to mirror S6;mirror 5 corresponds to mirror S3; mirror 6 corresponds to mirror S4;mirror 7 corresponds to the primary concave mirror SK1; and mirror 8corresponds to the secondary concave mirror SK2.

TABLE 1A Surface Radius Thickness Mode Object INFINITY 316.480 Mirror 1−375.233 −77.505 REFL Mirror 2 2976.73 51.007 REFL STOP INFINITY 0.000Mirror 3 127.889 −189.982 REFL Mirror 4 329.839 1029.934 REFL Mirror 5787.6 −596.052 REFL Mirror 6 735.437 1171.383 REFL Mirror 7 −1195.158−512.255 REFL Mirror 8 977.668 552.254 REFL Image INFINITY 0.000

TABLE 1B Surface K A B C Mirror 1 0.00000E+00 −3.72335E−09 −1.17134E−13 −9.45919E−19 Mirror 2 0.00000E+00 −6.42297E−08 5.78359E−13 −1.12102E−17Mirror 3 0.00000E+00 −1.89730E−07 1.46577E−11 −7.35930E−15 Mirror 40.00000E+00 −6.59877E−10 −4.46770E−15  −8.43588E−22 Mirror 5 0.00000E+00 6.80330E−10 8.62377E−15  7.97025E−20 Mirror 6 0.00000E+00  1.51444E−104.21253E−16  9.86205E−22 Mirror 7 0.00000E+00 −9.01450E−11 7.43085E−17−9.79557E−22 Mirror 8 0.00000E+00 −4.33573E−10 −6.45281E−16  1.20541E−22 Surface D E F G Mirror 1 2.64879E−22 −1.44452E−263.02340E−31 0.00000E+00 Mirror 2 1.41033E−20 −2.65285E−24 1.76103E−288.50988E−33 Mirror 3 4.29136E−18  4.55565E−22 6.01716E−23 −9.67457E−26 Mirror 4 −1.47803E−24   4.37901E−29 −7.78139E−34  6.26619E−39 Mirror 59.90660E−24 −3.49519E−27 2.27576E−31 −5.30361E−36  Mirror 6 2.49255E−27 3.14626E−33 1.55856E−38 5.58485E−45 Mirror 7 6.90221E−27 −3.91894E−321.37730E−37 −2.19834E−43  Mirror 8 6.77194E−28  1.92112E−32−7.82371E−38  1.09694E−43

Referring to FIG. 11, an embodiment of a projection objective 1100includes eight mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2, and has animage-side numerical aperture of 0.5 and an operating wavelength of 13.5nm. Mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2 are all asphericalmirrors. Projection objective 1100 images radiation from object plane103 to image plane 102 with a demagnification ratio of 4× and aresolution of about 17 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,711 mm.

Projection objective 1100 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 13 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.044λ. Image-side field curvature is 12 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S1 is a convexmirror; mirror S2 is a concave mirror; mirror S5 is a convex mirror;mirror S6 is a concave mirror; mirror S3 is a convex mirror; mirror S4is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror.

Mirrors S3, S4, SK1, and SK2 include openings. Opening A1 is located inmirror S3, opening A2 is located in mirror SK2, opening A3 is located inmirror SK1, and opening A4 is located in mirror S4. Mirrors S1, S2, S5,and S6 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 36% of the aperture radius.

The image-side free working distance is 69 mm. The object side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 of a chief ray of a central field point is 19.4°. The maximumangle of incidence of any ray on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 is 21.8°. The maximum range of incident angles on any of mirrorsS1, S2, S3, S4, S5, S6, SK1, and SK2 is 15.0°.

The size of the largest mirror in meridional section is 385 mm. The sizeof the largest mirror in the x-direction is 616 mm.

The mirrors are arranged so that projection objective 1100 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1000 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of four mirrors: mirror S1,mirror S2, mirror S5, and mirror S6. First partial objective 1010 formsan intermediate image Z1 in or close to mirror S4.

Second partial objective 1020 has a total of two mirrors: mirror S3, andmirror S4. Second partial objective 1020 forms an intermediate image Z2in or close to mirror S3.

Third partial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image in or close toimage plane 102.

An aperture stop is positioned near mirror S3.

Data for projection objective 1100 is presented in Table 2A and Table 2Bbelow. Table 2A presents optical data, while Table 2B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 2A and Table 2B, the mirror designations correlate as follows:mirror 1 corresponds to mirror S1; mirror 2 corresponds to mirror S2;mirror 3 corresponds to mirror S5; mirror 4 corresponds to mirror S6;mirror 5 corresponds to mirror S3; mirror 6 corresponds to mirror S4;mirror 7 corresponds to the primary concave mirror SK1; and mirror 8corresponds to the secondary concave mirror SK2.

TABLE 2A Surface Radius Thickness Mode Object INFINITY 762.134 Mirror 144367.928 −662.134 REFL Mirror 2 1027.348 717.444 REFL Mirror 3 122.696−209.209 REFL Mirror 4 298.792 645.481 REFL STOP INFINITY 0.000 Mirror 51184.237 −391.582 REFL Mirror 6 518.111 780.329 REFL Mirror 7 −834.844−288.328 REFL Mirror 8 612.533 357.344 REFL Image INFINITY 0.000

TABLE 2B Surface K A B Mirror 1 0.00000E+00 −7.47500E−11 −1.75668E−16Mirror 2 0.00000E+00 −1.89057E−11 −2.80932E−17 Mirror 3 0.00000E+004.36794E−08 −1.06646E−11 Mirror 4 0.00000E+00 2.82491E−10 8.34214E−15Mirror 5 0.00000E+00 −3.60521E−09 9.55167E−14 Mirror 6 0.00000E+003.17133E−10 1.58610E−15 Mirror 7 0.00000E+00 1.39054E−10 −7.02552E−16Mirror 8 0.00000E+00 −1.05535E−09 −1.09975E−15 Surface C D E Mirror 13.61103E−22 3.67940E−28 0.00000E+00 Mirror 2 −3.13881E−23 −4.81965E−290.00000E+00 Mirror 3 2.88089E−15 1.57635E−18 0.00000E+00 Mirror 41.25238E−19 6.61889E−25 4.85405E−29 Mirror 5 −3.43883E−18 −4.42296E−23−5.96479E−28 Mirror 6 7.12061E−21 2.79827E−26 2.00701E−31 Mirror 71.18760E−20 −6.15624E−26 5.37541E−31 Mirror 8 8.52603E−23 3.64425E−262.56412E−31

Referring to FIG. 12, an embodiment of a projection objective 1200includes eight mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2, and has animage-side numerical aperture of 0.5 and an operating wavelength of 13.5nm. Mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2 are all asphericalmirrors. Projection objective 1200 images radiation from object plane103 to image plane 102 with a demagnification ratio of 5× and aresolution of about 17 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,509 mm.

Projection objective 1200 has a ring-segment field. The image-side fieldwidth, d_(x), is 22 mm. The image-side field radius, d_(r), is 12.6 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.01λ. Image-side field curvature is 2 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S1 is a convexmirror; mirror S2 is a concave mirror; mirror S5 is a convex mirror;mirror S6 is a concave mirror; mirror S3 is a convex mirror; mirror S4is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror.

Mirrors S3, S4, SK1, and SK2 include openings. Opening A1 is located inmirror S3, opening A2 is located in mirror SK2, opening A3 is located inmirror SK1, and opening A4 is located in mirror S4. Mirrors S1, S2, S5,and S6 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 35% of the aperture radius.

The image-side free working distance A is 69 mm. The object-side freeworking distance is 104 mm.

The maximum angle of incidence on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 of a chief ray of a central field point is 23.1°. The maximumangle of incidence of any ray on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 is 26.6°. The maximum range of incident angles on any of mirrorsS1, S2, S3, S4, S5, S6, SK1, and SK2 is 16.0°.

The size of the largest mirror in meridional section is 394 mm. The sizeof the largest mirror in the x-direction is 669 mm.

The mirrors are arranged so that projection objective 1200 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1000 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of four mirrors: mirror S1,mirror S2, mirror S5, and mirror S6. First partial objective 1010 formsan intermediate image Z1 in or close to mirror S4.

Second partial objective 1020 has a total of two mirrors: mirror S3, andmirror S4. Second partial objective 1020 forms an intermediate image Z2in or close to mirror S3.

Third partial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image in or close toimage plane 102.

An aperture stop is positioned near mirror S3.

Data for projection objective 1200 is presented in Table 3A and Table 3Bbelow. Table 3A presents optical data, while Table 3B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 3A and Table 3B, the mirror designations correlate as follows:mirror 1 corresponds to mirror S1; mirror 2 corresponds to mirror S2;mirror 3 corresponds to mirror S5; mirror 4 corresponds to mirror S6;mirror 5 corresponds to mirror S3; mirror 6 corresponds to mirror S4;mirror 7 corresponds to the primary concave mirror SK1; and mirror 8corresponds to the secondary concave mirror SK2.

TABLE 3A Surface Radius Thickness Mode Object INFINITY 546.051 Mirror 11813.761 −442.075 REFL Mirror 2 659.925 484.056 REFL Mirror 3 124.229−230.251 REFL Mirror 4 297.991 681.239 REFL STOP INFINITY 0.000 Mirror 51044.821 −388.855 REFL Mirror 6 513.480 790.082 REFL Mirror 7 −788.712−300.808 REFL Mirror 8 679.931 369.811 REFL Image INFINITY 0.000

TABLE 3B Surface K A B Mirror 1 0.00000E+00 −1.19695E−10 −8.52500E−16Mirror 2 0.00000E+00 −3.36861E−12 −7.92767E−18 Mirror 3 0.00000E+009.84422E−08 1.34188E−11 Mirror 4 0.00000E+00 1.55138E−09 3.79123E−14Mirror 5 0.00000E+00 −4.54986E−09 −1.08708E−13 Mirror 6 0.00000E+001.67047E−10 5.41737E−16 Mirror 7 0.00000E+00 5.45494E−10 1.78568E−15Mirror 8 0.00000E+00 −5.70218E−10 1.44136E−15 Surface C D E Mirror 17.78764E−22 2.36289E−26 0.00000E+00 Mirror 2 −1.47046E−23 −1.76721E−280.00000E+00 Mirror 3 1.19275E−15 7.18150E−19 0.00000E+00 Mirror 47.88066E−19 1.04079E−23 8.66992E−28 Mirror 5 −1.73422E−18 −5.79768E−232.10975E−27 Mirror 6 1.67663E−21 5.27011E−27 2.40781E−32 Mirror 79.69823E−21 1.84324E−26 −1.96285E−32 Mirror 8 6.92822E−21 −1.65770E−264.86553E−32

Referring to FIG. 13, an embodiment of a projection objective 1300includes eight mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2, and has animage-side numerical aperture of 0.5 and an operating wavelength of 13.5nm. Mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2 are all asphericalmirrors. Projection objective 1300 images radiation from object plane103 to image plane 102 with a demagnification ratio of 6× and aresolution of about 17 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,508 mm.

Projection objective 1300 has a ring-segment field. The image-side fieldwidth, d_(x), is 18 mm. The image-side field radius, d_(r), is 10.5 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.006λ. Image-side field curvature is 2 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S1 is a convexmirror; mirror S2 is a concave mirror; mirror S5 is a convex mirror;mirror S6 is a concave mirror; mirror S3 is a convex mirror; mirror S4is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror.

Mirrors S3, S4, SK1, and SK2 include openings. Opening A1 is located inmirror S3, opening A2 is located in mirror SK2, opening A3 is located inmirror SK1, and opening A4 is located in mirror S4. Mirrors S1, S2, S5,and S6 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 31% of the aperture radius.

The image-side free working distance is 69 mm. The object-side freeworking distance is 102 mm.

The maximum angle of incidence on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 of a chief ray of a central field point is 20.0°. The maximumangle of incidence of any ray on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 is 22.3°. The maximum range of incident angles on any of mirrorsS1, S2, S3, S4, S5, S6, SK1, and SK2 is 13.6°.

The size of the largest mirror in meridional section is 396 mm. The sizeof the largest mirror in the x-direction is 575 mm.

The mirrors are arranged so that projection objective 1300 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1000 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of four mirrors: mirror S1,mirror S2, mirror S5, and mirror S6. First partial objective 1010 formsan intermediate image Z1 in or close to mirror S4.

Second partial objective 1020 has a total of two mirrors: mirror S3, andmirror S4. Second partial objective 1020 forms an intermediate image Z2in or close to mirror S3.

Third partial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image in or close toimage plane 102.

An aperture stop is positioned near mirror S3.

Data for projection objective 1300 is presented in Table 4A and Table 4Bbelow. Table 4A presents optical data, while Table 4B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 4A and Table 4B, the mirror designations correlate as follows:mirror 1 corresponds to mirror S1; mirror 2 corresponds to mirror S2;mirror 3 corresponds to mirror S5; mirror 4 corresponds to mirror S6;mirror 5 corresponds to mirror S3; mirror 6 corresponds to mirror S4;mirror 7 corresponds to the primary concave mirror SK1; and mirror 8corresponds to the secondary concave mirror SK2.

TABLE 4A Surface Radius Thickness Mode Object INFINITY 541.176 Mirror 11654.286 −438.932 REFL Mirror 2 662.227 486.164 REFL Mirror 3 124.521−234.334 REFL Mirror 4 296.656 684.148 REFL STOP INFINITY 0.000 Mirror 51078.372 −388.948 REFL Mirror 6 513.362 789.957 REFL Mirror 7 −788.995−300.590 REFL Mirror 8 680.459 369.601 REFL Image INFINITY 0.000

TABLE 4B Surface K A B Mirror 1 0.00000E+00 −2.36631E−10 −8.55660E−16Mirror 2 0.00000E+00 −5.67713E−12 −1.95884E−17 Mirror 3 0.00000E+001.11517E−07 1.37540E−11 Mirror 4 0.00000E+00 1.49061E−09 3.64316E−14Mirror 5 0.00000E+00 −3.81551E−09 −9.20087E−14 Mirror 6 0.00000E+001.71591E−10 5.38871E−16 Mirror 7 0.00000E+00 5.11749E−10 1.71998E−15Mirror 8 0.00000E+00 −5.78016E−10 1.45805E−15 Surface C D E Mirror 1−2.47185E−21 7.32017E−26 0.00000E+00 Mirror 2 −5.87523E−23 −3.53329E−280.00000E+00 Mirror 3 1.28574E−15 7.20115E−19 0.00000E+00 Mirror 47.29870E−19 1.30379E−23 6.71117E−28 Mirror 5 −1.57361E−18 −5.49020E−231.99214E−27 Mirror 6 1.53854E−21 4.80288E−27 1.35503E−32 Mirror 79.34714E−21 1.84180E−26 −2.13432E−32 Mirror 8 7.06565E−21 −1.76539E−264.32302E−32

Referring to FIG. 14, an embodiment of a projection objective 1400includes eight mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2, and has animage-side numerical aperture of 0.5 and an operating wavelength of 13.5nm. Mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2 are all asphericalmirrors. Projection objective 1000 images radiation from object plane103 to image plane 102 with a demagnification ratio of 8× and aresolution of about 17 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 2,000 mm.

Projection objective 1400 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 10.5 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.033λ. Image-side field curvature is 7 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S1 is a convexmirror; mirror S2 is a concave mirror; mirror S5 is a convex mirror;mirror S6 is a concave mirror; mirror S3 is a convex mirror; mirror S4is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror. Mirror S1 has a very large radius of curvature such as,for example, a radius of curvature greater than 10 m. Mirror S1 may besubstituted by a planar mirror or a concave mirror with similarly largeradius of curvature in some embodiments.

Mirrors S3, S4, SK1, and SK2 include openings. Opening A1 is located inmirror S3, opening A2 is located in mirror SK2, opening A3 is located inmirror SK1, and opening A4 is located in mirror S4. Mirrors S1, S2, S5,and S6 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 21% of the aperture radius.

The image-side free working distance is 61 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 of a chief ray of a central field point is 15.9°. The maximumangle of incidence of any ray on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 is 17.9°. The maximum range of incident angles on any of mirrorsS1, S2, S3, S4, S5, S6, SK1, and SK2 is 10.6°.

The size of the largest mirror in meridional section is 574 mm. The sizeof the largest mirror in the x-direction is 602 mm.

The mirrors are arranged so that projection objective 1400 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1000 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of four mirrors: mirror S1,mirror S2, mirror S5, and mirror S6. First partial objective 1010 formsan intermediate image Z1 in or close to mirror S4.

Second partial objective 1020 has a total of two mirrors: mirror S3, andmirror S4. Second partial objective 1020 forms an intermediate image Z2in or close to mirror S3.

Third partial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image in or close toimage plane 102.

An aperture stop is positioned near mirror S3.

Data for projection objective 1400 is presented in Table 5A and Table 5Bbelow. Table 5A presents optical data, while Table 5B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 5A and Table 5B, the mirror designations correlate as follows:mirror 1 corresponds to mirror S1; mirror 2 corresponds to mirror S2;mirror 3 corresponds to mirror S5; mirror 4 corresponds to mirror S6;mirror 5 corresponds to mirror S3; mirror 6 corresponds to mirror S4;mirror 7 corresponds to the primary concave mirror SK1; and mirror 8corresponds to the secondary concave mirror SK2.

TABLE 5A Surface Radius Thickness Mode Object INFINITY 718.810 Mirror 115385.939 −618.810 REFL Mirror 2 1044.688 695.118 REFL Mirror 3 147.529−266.967 REFL Mirror 4 330.139 870.985 REFL STOP INFINITY 0.000 Mirror 51943.227 −572.412 REFL Mirror 6 750.946 1111.744 REFL Mirror 7 −1056.656−459.333 REFL Mirror 8 963.397 520.863 REFL Image INFINITY 0.000

TABLE 5B Surface K A B C D E F G Mirror 1 0.00000E+00 1.03935E−092.87706E−15 2.44500E−21 −2.92087E−26 1.22174E−30 −2.07471E−360.00000E+00 Mirror 2 0.00000E+00 1.49306E−10 4.00929E−18 1.48243E−224.70420E−28 −1.12401E−33 1.99786E−39 0.00000E+00 Mirror 3 0.00000E+001.18016E−07 −3.53495E−12 −4.55098E−17 4.31101E−19 −1.46428E−312.97986E−26 0.00000E+00 Mirror 4 0.00000E+00 −2.54082E−09 5.38905E−15−4.39113E−19 1.06326E−23 −1.79423E−28 −1.59791E−33 0.00000E+00 Mirror 50.00000E+00 −4.90575E−10 −1.53636E−14 −6.47129E−19 −3.42940E−24−1.75351E−28 8.76415E−33 0.00000E+00 Mirror 6 0.00000E+00 1.36782E−101.60457E−16 −3.92581E−25 −2.81150E−29 −4.22172E−33 2.23604E−380.00000E+00 Mirror 7 0.00000E+00 1.87167E−10 7.58028E−16 1.89696E−217.95754E−27 −8.87929E−33 −5.33665E−40 0.00000E+00 Mirror 8 0.00000E+00−3.76514E−10 1.37610E−15 1.26961E−21 −6.32171E−27 −3.06485E−321.56764E−37 0.00000E+00

Referring to FIG. 15A, an embodiment of a projection objective 1500includes eight mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2, and has animage-side numerical aperture of 0.6 and an operating wavelength of 13.5nm. Mirrors S1, S2, S3, S4, S5, S6, SK1, and SK2 are all asphericalmirrors. Projection objective 1500 images radiation from object plane103 to image plane 102 with a demagnification ratio of 8× and aresolution of about 14 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 2,500 mm.

Projection objective 1500 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 15.0 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.017λ. Image-side field curvature is 1 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S1 is a convexmirror; mirror S2 is a concave mirror; mirror S5 is a convex mirror;mirror S6 is a concave mirror; mirror S3 is a convex mirror; mirror S4is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror.

Mirrors S3, S4, SK1, and SK2 include openings. Opening A1 is located inmirror S3, opening A2 is located in mirror SK2, opening A3 is located inmirror SK1, and opening A4 is located in mirror S4. Mirrors S1, S2, S5,and S6 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 22% of the aperture radius.

The image-side free working distance is 55 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 of a chief ray of a central field point is 28.3°. The maximumangle of incidence of any ray on mirrors S1, S2, S3, S4, S5, S6, SK1,and SK2 is 36.6°. The maximum range of incident angles on any of mirrorsS1, S2, S3, S4, S5, S6, SK1, and SK2 is 16.6°.

The size of the largest mirror in meridional section is 778 mm. The sizeof the largest mirror in the x-direction is 806 mm.

The mirrors are arranged so that projection objective 1500 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1000 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of four mirrors: mirror S1,mirror S2, mirror S5, and mirror S6. First partial objective 1010 formsan intermediate image Z1 in or close to mirror S4.

Second partial objective 1020 has a total of two mirrors: mirror S3, andmirror S4. Second partial objective 1020 forms an intermediate image Z2in or close to mirror S3.

Third partial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image in or close toimage plane 102.

Data for projection objective 1500 is presented in Table 6A and Table 6Bbelow. Table 6A presents optical data, while Table 6B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 6A and Table 6B, the mirror designations correlate as follows:mirror 1 corresponds to mirror S1; mirror 2 corresponds to mirror S2;mirror 3 corresponds to mirror S5; mirror 4 corresponds to mirror S6;mirror 5 corresponds to mirror S3; mirror 6 corresponds to mirror S4;mirror 7 corresponds to the primary concave mirror SK1; and mirror 8corresponds to the secondary concave mirror SK2.

TABLE 6A Surface Radius Thickness Mode Object INFINITY 257.565 Mirror 1384.091 −157.565 REFL Mirror 2 503.282 1033.640 REFL Mirror 3 319.62−732.625 REFL Mirror 4 847.883 1465.334 REFL STOP INFINITY 0.000 Mirror5 2114.302 −643.385 REFL Mirror 6 842.763 1221.637 REFL Mirror 7−1165.231 −498.252 REFL Mirror 8 1000.806 553.650 REFL Image INFINITY0.000

TABLE 6B Surface K A B C D E F G Mirror 1 0.00000E+00 −1.77573E−093.48952E−15 −6.57559E−19 2.03449E−23 −3.58406E−28 2.56981E−330.00000E+00 Mirror 2 0.00000E+00 −1.90688E−10 −1.12202E−16 −8.55933E−214.01912E−26 −1.85143E−31 0.00000E+00 0.00000E+00 Mirror 3 0.00000E+008.18543E−09 1.94772E−13 −1.20733E−17 5.33524E−21 −1.38304E−241.60705E−28 0.00000E+00 Mirror 4 0.00000E+00 −6.32144E−11 −3.16379E−17−1.24533E−22 2.11929E−28 −1.37968E−33 4.50488E−39 0.00000E+00 Mirror 50.00000E+00 5.20532E−10 −3.03678E−15 5.56242E−21 −2.48900E−254.49855E−30 −1.02965E−34 0.00000E+00 Mirror 6 0.00000E+00 8.24359E−111.21698E−16 1.72019E−22 2.88661E−28 2.26755E−34 1.46632E−39 0.00000E+00Mirror 7 0.00000E+00 1.04209E−10 5.94759E−17 3.29996E−22 −9.32494E−297.01284E−34 1.83576E−39 0.00000E+00 Mirror 8 0.00000E+00 −2.52357E−108.47992E−17 5.92488E−22 −1.30631E−27 1.75865E−33 6.32541E−40 0.00000E+00

Referring to FIG. 15B, an embodiment of a projection objective 1510includes eight mirrors SP1-SP8, and has an image-side numerical apertureof 0.6 and an operating wavelength of 13.5 nm. Mirrors SP1-SP8 are allaspherical mirrors. Projection objective 1510 images radiation fromobject plane 103 to image plane 102 with a demagnification ratio of 8×and a resolution of about 14 nm. The optical axis in relation to whichthe projection objective is rotationally symmetric is identified as HA,and the overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 2,000 mm.

Projection objective 1510 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 26.5 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.018λ. Image-side field curvature is 2 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror SP1 is a concavemirror; mirror SP2 is a concave mirror; mirror SP3 is a convex mirror;mirror SP4 is a concave mirror; mirror SP5 is a convex mirror; mirrorSP6 is a concave mirror; mirror SP7 is a concave mirror; and mirror SP8is a concave mirror.

Mirrors SP7 and SP8 include openings. Mirrors SP1-SP6 do not includeopenings. The resulting obscuration radius that provides afield-independent obscuration is 22% of the aperture radius.

The image-side free working distance is 15 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors SP1-SP8 of a chief ray of acentral field point is 30.1°. The maximum angle of incidence of any rayon mirrors SP1-SP8 is 31.5°. The maximum range of incident angles on anyof mirrors SP1-SP8 is 29.0°.

The size of the largest mirror in meridional section is 621 mm. The sizeof the largest mirror in the x-direction is 668 mm.

The mirrors are arranged so that projection objective 1510 contains twopartial objectives: a first partial objective 1010, and a second partialobjective 1020. Accordingly, projection objective 1000 produces threepupil planes and two intermediate images. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop, atthe position of mirror SP2, for example.

First partial objective 1010 has a total of six mirrors: mirror SP1,mirror SP2, mirror SP3, mirror SP4, mirror SP5, and mirror SP6. Firstpartial objective 1010 forms an intermediate image Z1. First partialobjective 1010 also forms an intermediate image Z2.

An aperture stop B is positioned on or close to mirror SP2. In thisembodiment, aperture stop B can be alternatively be positioned betweenmirrors SP7 and SP8, because a conjugate stop plane is located there.

Data for projection objective 1510 is presented in Table 7A and Table 7Bbelow. Table 7A presents optical data, while Table 7B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 7A and Table 7B, the mirror designations correlate as follows:mirror 1 corresponds to mirror SP1; mirror 2 corresponds to mirror SP2;mirror 3 corresponds to mirror SP3; mirror 4 corresponds to mirror SP4;mirror 5 corresponds to mirror SP5; mirror 6 corresponds to mirror SP6;mirror 7 corresponds to mirror SP7; and mirror 8 corresponds to mirrorSP8.

TABLE 7A Surface Radius Thickness Mode Object INFINITY 922.791 Mirror 1−3699.835 −722.791 REFL STOP INFINITY 0.000 Mirror 2 1396.642 722.791REFL Mirror 3 326.694 −209.599 REFL Mirror 4 495.849 808.165 REFL Mirror5 268.532 −498.566 REFL Mirror 6 545.559 962.209 REFL Mirror 7 −1362.684−455.200 REFL Mirror 8 753.748 470.200 REFL Image INFINITY 0.000

TABLE 7B Surface K A B C D E F G Mirror 1 0.00000E+00 4.62106E−10−1.60960E−15 5.15302E−21 −4.68484E−26 7.39174E−31 −4.68562E−360.00000E+00 Mirror 2 0.00000E+00 5.34180E−11 −1.73246E−15 8.91595E−20−1.14886E−23 5.55335E−28 −1.14958E−32 0.00000E+00 Mirror 3 0.00000E+00−3.78083E−09 −1.60946E−14 1.44926E−18 −6.49583E−23 1.53314E−27−1.44417E−32 0.00000E+00 Mirror 4 0.00000E+00 1.29725E−10 −4.33242E−153.55197E−20 −1.55220E−25 2.37719E−32 1.28111E−36 0.00000E+00 Mirror 50.00000E+00 −5.41995E−09 5.52456E−13 2.52759E−17 8.89081E−22 3.94133E−26−4.47051E−30 0.00000E+00 Mirror 6 0.00000E+00 −3.73334E−11 −1.02668E−16−2.99968E−22 −1.44127E−27 2.92660E−33 −3.35888E−38 0.00000E+00 Mirror 70.00000E+00 7.83478E−10 1.90282E−15 4.06118E−21 8.72416E−27 4.28608E−322.15963E−37 0.00000E+00 Mirror 8 0.00000E+00 1.12087E−10 2.96721E−166.94605E−22 1.93827E−27 −5.92415E−34 2.66223E−38 0.00000E+00

Referring to FIG. 15C, an embodiment of a projection objective 1520includes eight mirrors SP1-SP8, and has an image-side numerical apertureof 0.6 and an operating wavelength of 13.5 nm. Mirrors SP1-SP8 are allaspherical mirrors. Projection objective 1520 images radiation fromobject plane 103 to image plane 102 with a demagnification ratio of 8×and a resolution of about 14 nm. The optical axis in relation to whichthe projection objective is rotationally symmetric is identified as HA,and the overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,846 mm.

Projection objective 1520 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 16.25 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.015λ. Image-side field curvature is 1 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror SP1 is a concavemirror; mirror SP2 is a concave mirror; mirror SP3 is a convex mirror;mirror SP4 is a concave mirror; mirror SP5 is a convex mirror; mirrorSP6 is a concave mirror; mirror SP7 is a concave mirror; and mirror SP8is a concave mirror.

Mirrors SP7 and SP8 include openings. Mirrors SP1-SP6 do not includeopenings. The resulting obscuration radius that provides afield-independent obscuration is 29% of the aperture radius.

The image-side free working distance is 40 mm. The object-side freeworking distance is 322 mm.

The maximum angle of incidence on mirrors SP1-SP8 of a chief ray of acentral field point is 21.0°. The maximum angle of incidence of any rayon mirrors SP1-SP8 is 25.2°. The maximum range of incident angles on anyof mirrors SP1-SP8 is 24.9°.

The size of the largest mirror in meridional section is 682 mm. The sizeof the largest mirror in the x-direction is 694 mm.

The mirrors are arranged so that projection objective 1520 contains twopartial objectives: a first partial objective 1010, and a second partialobjective 1020. Accordingly, projection objective 1000 produces threepupil planes and two intermediate images. At least one of the pupilplanes is accessible for positioning an aperture stop.

First partial objective 1010 has a total of six mirrors: mirror SP1,mirror SP2, mirror SP3, mirror SP4, mirror SP5, and mirror SP6. Firstpartial objective 1010 forms an intermediate image Z1. First partialobjective 1010 also forms an intermediate image Z2.

An aperture stop B is positioned between concave mirrors SP7 and SP8. Inthe current embodiment, the mirror with the shortest axial distance toobject plane 103, as measured along the principal axis HA of theobjective, is not mirror SP2 but mirror SP4. As a result, a particularlylong drift distance is made available between fourth mirror SP4 andfifth mirror SP5, which has the consequence that the angles of incidenceon the mirrors SP4 and SP5 are small.

Data for projection objective 1520 is presented in Table 8A and Table 8Bbelow. Table 8A presents optical data, while Table 8B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 8A and Table 8B, the mirror designations correlate as follows:mirror 1 corresponds to mirror SP1; mirror 2 corresponds to mirror SP2;mirror 3 corresponds to mirror SP3; mirror 4 corresponds to mirror SP4;mirror 5 corresponds to mirror SP5; mirror 6 corresponds to mirror SP6;mirror 7 corresponds to mirror SP7; and mirror 8 corresponds to mirrorSP8.

TABLE 8A Surface Radius Thickness Mode Object INFINITY 798.296 Mirror 1−1827.312 −361.283 REFL Mirror 2 2771.147 361.283 REFL Mirror 3 316.676−476.449 REFL Mirror 4 775.124 1039.440 REFL Mirror 5 372.661 −462.991REFL Mirror 6 471.732 908.105 REFL Mirror 7 −8480.523 −146.460 REFL STOPINFINITY −357.622 Mirror 8 715.42 544.082 REFL Image INFINITY 0.000

TABLE 8B Surface K A B C D E F G Mirror 1 0.00000E+00 −1.45626E−096.40290E−16 2.94780E−20 3.73960E−25 −1.56367E−30 0.00000E+00 0.00000E+00Mirror 2 0.00000E+00 9.31344E−09 1.78433E−13 6.07073E−18 −1.28696E−211.16367E−25 −4.40517E−30 0.00000E+00 Mirror 3 0.00000E+00 1.20767E−094.63422E−14 1.06360E−18 1.78247E−23 4.71695E−28 1.30944E−32 0.00000E+00Mirror 4 0.00000E+00 −3.94048E−12 −4.34341E−18 −2.29083E−24 −6.39796E−301.00689E−35 0.00000E+00 0.00000E+00 Mirror 5 0.00000E+00 7.23867E−084.59128E−12 4.03493E−16 4.83186E−20 −2.96561E−32 1.74256E−27 0.00000E+00Mirror 6 0.00000E+00 4.58357E−10 4.09942E−15 3.25541E−20 2.52331E−252.36217E−30 1.50441E−35 0.00000E+00 Mirror 7 0.00000E+00 7.13645E−10−4.17082E−15 1.96723E−20 −2.00951E−26 −4.39472E−31 2.79897E−360.00000E+00 Mirror 8 0.00000E+00 −2.07223E−11 −3.53129E−17 −8.11682E−233.99332E−29 −5.92386E−34 1.39149E−39 0.00000E+00

Referring to FIG. 15D, an embodiment of a projection objective 1530includes eight mirrors SP1-SP8, and has an image-side numerical apertureof 0.6 and an operating wavelength of 13.4 nm. Mirrors SP1-SP8 are allaspherical mirrors. Projection objective 1530 images radiation fromobject plane 103 to image plane 102 with a demagnification ratio of 8×and a resolution of about 14 nm. The optical axis in relation to whichthe projection objective is rotationally symmetric is identified as HA,and the overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 2,000 mm.

Projection objective 1530 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 18.75 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.025λ. Image-side field curvature is 5 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror SP1 is a concavemirror; mirror SP2 is a convex mirror; mirror SP3 is a concave mirror;mirror SP4 is a convex mirror; mirror SP5 is a convex mirror; mirror SP6is a concave mirror; mirror SP7 is a concave mirror; and mirror SP8 is aconcave mirror.

Mirrors SP7 and SP8 include openings. Mirrors SP1-SP6 do not includeopenings. The resulting obscuration radius that provides afield-independent obscuration is 26% of the aperture radius.

The image-side free working distance is 41 mm. The object-side freeworking distance is 402 mm.

The maximum angle of incidence on mirrors SP1-SP8 of a chief ray of acentral field point is 26.1°. The maximum angle of incidence of any rayon mirrors SP1-SP8 is 29.8°. The maximum range of incident angles on anyof mirrors SP1-SP8 is 21.0°.

The size of the largest mirror in meridional section is 753 mm. The sizeof the largest mirror in the x-direction is 765 mm.

The mirrors are arranged so that projection objective 1530 contains twopartial objectives: a first partial objective 1010, and a second partialobjective 1020. Accordingly, projection objective 1530 produces threepupil planes and two intermediate images. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, an obscuration stop can be positioned between mirrors SP1 andSP2.

First partial objective 1010 has a total of six mirrors: mirror SP1,mirror SP2, mirror SP3, mirror SP4, mirror SP5, and mirror SP6. Firstpartial objective 1010 forms an intermediate image Z1. First partialobjective 1010 also forms an intermediate image Z2.

An aperture stop B is positioned between concave mirrors SP7 and SP8. Insome embodiments, aperture stop B can also be positioned between mirrorsSP1 and SP2, or directly on mirror SP1, or directly on mirror SP2.

Data for projection objective 1530 is presented in Table 9A and Table 9Bbelow. Table 9A presents optical data, while Table 9B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 9A and Table 9B, the mirror designations correlate as follows:mirror 1 corresponds to mirror SP1; mirror 2 corresponds to mirror SP2;mirror 3 corresponds to mirror SP3; mirror 4 corresponds to mirror SP4;mirror 5 corresponds to mirror SP5; mirror 6 corresponds to mirror SP6;mirror 7 corresponds to mirror SP7; and mirror 8 corresponds to mirrorSP8.

TABLE 9A Surface Radius Thickness Mode Object INFINITY 880.361 Mirror 1−875.368 −478.259 REFL Mirror 2 −690.520 1092.679 REFL Mirror 3 −977.378−551.779 REFL Mirror 4 −833.448 458.600 REFL Mirror 5 358.753 −471.240REFL Mirror 6 523.860 1028.166 REFL Mirror 7 −5262.591 −149.862 REFLSTOP INFINITY −407.152 Mirror 8 814.485 598.487 REFL Image INFINITY0.000

TABLE 9B Surface K A B C D E F G Mirror 1 0.00000E+00 −9.68983E−111.30663E−15 −4.94071E−20 −3.11075E−25 7.43387E−30 −1.22653E−340.00000E+00 Mirror 2 0.00000E+00 2.94527E−09 9.63566E−14 −4.32741E−18−1.24960E−22 1.48734E−26 −4.81981E−31 0.00000E+00 Mirror 3 0.00000E+00−1.03936E−10 5.36156E−16 −1.65908E−21 3.13335E−27 −3.65847E−332.78395E−39 0.00000E+00 Mirror 4 0.00000E+00 1.24373E−09 2.24555E−14−3.21919E−18 1.45549E−22 −2.80273E−27 1.97890E−32 0.00000E+00 Mirror 50.00000E+00 4.32193E−08 1.67170E−12 9.36696E−17 1.12895E−20 −5.38537E−252.00528E−28 0.00000E+00 Mirror 6 0.00000E+00 6.52219E−12 −3.83205E−16−1.68489E−21 −4.41623E−27 5.82970E−33 −9.43009E−38 0.00000E+00 Mirror 70.00000E+00 4.88652E−10 1.07810E−15 2.49482E−21 7.45586E−27 1.58318E−332.42322E−37 0.00000E+00 Mirror 8 0.00000E+00 1.69034E−11 8.05549E−171.52452E−22 3.07949E−28 3.98761E−35 2.18360E−39 0.00000E+00

Referring to FIG. 15E, an embodiment of a projection objective 1540includes eight mirrors SP1-SP8, and has an image-side numerical apertureof 0.7 and an operating wavelength of 13.5 nm. Mirrors SP1-SP8 are allaspherical mirrors. Projection objective 1540 images radiation fromobject plane 103 to image plane 102 with a demagnification ratio of 8×and a resolution of about 12 nm. The optical axis in relation to whichthe projection objective is rotationally symmetric is identified as HA,and the overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,974 mm.

Projection objective 1540 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 18.0 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.021λ. Image-side field curvature is 1 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror SP1 is a concavemirror; mirror SP2 is a concave mirror; mirror SP3 is a concave mirror;mirror SP4 is a convex mirror; mirror SP5 is a convex mirror; mirror SP6is a concave mirror; mirror SP7 is a concave mirror; and mirror SP8 is aconcave mirror. The radius of curvature of mirror SP2 is sufficientlylarge that a planar mirror, or a concave mirror having a similarly largeradius of curvature, can also be used.

Mirrors SP7 and SP8 include openings. Mirrors SP1-SP6 do not includeopenings. The resulting obscuration radius that provides afield-independent obscuration is 23% of the aperture radius.

The image-side free working distance is 41 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors SP1-SP8 of a chief ray of acentral field point is 23.9°. The maximum angle of incidence of any rayon mirrors SP1-SP8 is 26.7°. The maximum range of incident angles on anyof mirrors SP1-SP8 is 23.3°.

The size of the largest mirror in meridional section is 904 mm. The sizeof the largest mirror in the x-direction is 916 mm.

The mirrors are arranged so that projection objective 1540 contains twopartial objectives: a first partial objective 1010, and a second partialobjective 1020. Accordingly, projection objective 1000 produces threepupil planes and two intermediate images. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, an obscuration stop can be positioned between mirrors SP1 andSP2.

First partial objective 1010 has a total of six mirrors: mirror SP1,mirror SP2, mirror SP3, mirror SP4, mirror SP5, and mirror SP6. Firstpartial objective 1010 forms an intermediate image Z1 in a positionbetween mirrors SP2 and SP3, and at a lower border of mirror SP4. Thisconfiguration permits the ray-bundle cross section at mirror SP4 to bekept small. First partial objective 1010 also forms an intermediateimage Z2.

An aperture stop B is positioned between concave mirrors SP7 and SP8.

Data for projection objective 1540 is presented in Table 10A and Table10B below. Table 10A presents optical data, while Table 10B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 10A and Table 10B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror SP1; mirror 2 corresponds tomirror SP2; mirror 3 corresponds to mirror SP3; mirror 4 corresponds tomirror SP4; mirror 5 corresponds to mirror SP5; mirror 6 corresponds tomirror SP6; mirror 7 corresponds to mirror SP7; and mirror 8 correspondsto mirror SP8.

TABLE 10A Surface Radius Thickness Mode Object INFINITY 810.260 Mirror 1−1005.764 −710.260 REFL Mirror 2 9426.007 1272.991 REFL Mirror 3−1182.815 −429.596 REFL Mirror 4 −11133.428 450.166 REFL Mirror 5186.619 −433.300 REFL Mirror 6 477.126 972.102 REFL Mirror 7 −4183.615−150.374 REFL STOP INFINITY −408.999 Mirror 8 818.267 600.845 REFL ImageINFINITY 0.000

TABLE 10B Surface K A B C D E F G Mirror 1 0.00000E+00 3.11825E−103.24549E−15 −6.83571E−20 1.72371E−24 −4.87613E−29 5.82893E−340.00000E+00 Mirror 2 0.00000E+00 −2.27912E−09 −4.60552E−15 −2.48079E−196.51533E−24 −1.43666E−28 1.04325E−33 0.00000E+00 Mirror 3 0.00000E+00−5.54875E−11 1.84013E−16 −8.66678E−22 1.11987E−27 0.00000E+000.00000E+00 0.00000E+00 Mirror 4 0.00000E+00 −3.87307E−10 1.79298E−15−3.85784E−20 3.55401E−25 −1.54989E−30 0.00000E+00 0.00000E+00 Mirror 50.00000E+00 −5.50749E−10 −6.08907E−13 4.73842E−17 −1.32381E−202.64772E−24 −2.26591E−28 0.00000E+00 Mirror 6 0.00000E+00 4.07407E−102.55564E−15 1.36374E−20 9.58842E−26 −5.38128E−32 7.68501E−36 0.00000E+00Mirror 7 0.00000E+00 3.47533E−10 3.22160E−16 1.16439E−21 6.85290E−283.55319E−33 2.83137E−38 0.00000E+00 Mirror 8 0.00000E+00 −1.97225E−112.09194E−17 8.09962E−23 9.92467E−29 6.06015E−34 −1.21955E−39 3.99272E−45

Referring to FIG. 16, an embodiment of a projection objective 1600includes ten mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1, andSK2, and has an image-side numerical aperture of 0.75 and an operatingwavelength of 13.5 nm. Mirrors S10, S20, S30, S40, S50, S60, S70, S80,SK1, and SK2 are all aspherical mirrors. Projection objective 1600images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 11 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is2,508 mm.

Projection objective 1600 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 30.75 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.013λ. Image-side field curvature is less than 1 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S10 is a convexmirror; mirror S20 is a concave mirror; mirror S50 is a convex mirror;mirror S60 is a concave mirror; mirror S70 is a concave mirror; mirrorS80 is a convex mirror; mirror S30 is a convex mirror; mirror S40 is aconcave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror. Mirror S10 has a radius of curvature larger than 10,000mm.

In some embodiments, mirror S10 can be replaced with a planar mirror, ora concave mirror having a similarly large radius of curvature. Forexample, in some embodiments. The order and curvature of mirrorsaccording to the path of radiation from object plane 103 to image plane102 may be as follows: mirror S10 is a concave mirror; mirror S20 is aconcave mirror; mirror S50 is a convex mirror; mirror S60 is a concavemirror; mirror S70 is a concave mirror; mirror S80 is a convex mirror;mirror S30 is a convex mirror; mirror S40 is a concave mirror; mirrorSK1 is a concave mirror; and mirror SK2 is a concave mirror. In otherembodiments, for example, The order and curvature of mirrors accordingto the path of radiation from object plane 103 to image plane 102 may beas follows: mirror S10 is a planar mirror; mirror S20 is a concavemirror; mirror S50 is a convex mirror; mirror S60 is a concave mirror;mirror S70 is a concave mirror; mirror S80 is a convex mirror; mirrorS30 is a convex mirror; mirror S40 is a concave mirror; mirror SK1 is aconcave mirror; and mirror SK2 is a concave mirror.

Mirrors S30, S40, S70, SK1, and SK2 include openings. Mirrors S10, S20,S50, S60, and S80 do not include openings. The resulting obscurationradius that provides a field-independent obscuration is 55% of theaperture radius.

The image-side free working distance is 41 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S10, S20, S30 S40, S50, S60,S70, S80, SK1, and SK2 of a chief ray of a central field point is 32.9°.The maximum angle of incidence of any ray on mirrors S10, S20, S30, S40,S50, S60, S70, S80, SK1, and SK2 is 45.1°. The maximum range of incidentangles on any of mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1,and SK2 is 28.0°.

The size of the largest mirror in meridional section is 932 mm. The sizeof the largest mirror in the x-direction is 1034 mm.

The mirrors are arranged so that projection objective 1600 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1600 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop. At least one of the pupil planes isaccessible for positioning an obscuration stop. For example, anobscuration stop can be positioned at mirror S20.

First partial objective 1010 has a total of six mirrors: mirror S10,mirror S20, mirror S50, mirror S60, mirror S70, and mirror S80. Firstpartial objective 1010 forms an intermediate image Z1 in a positionbetween mirrors S40 and S70, which may be at or near either or bothmirrors. The Z1 image is demagnified 1.85×. Second partial objective1020 has a total of two mirrors: mirror S30, and mirror S40. Secondpartial objective 1020 forms an intermediate image Z2 at or near theposition of mirror S30. The Z2 image is demagnified 3.38×. Third partialobjective 1030 has a total of two mirrors: mirror SK1, and mirror SK2.Third partial objective 1030 forms an image at or near the position ofimage plane 102. This image is demagnified 1.3×.

The embodiment shown is a pupil-obscurated system with at least onemirror with an opening for the passage of a bundle of rays, whereaperture stop B, positioned on mirror S20, is positioned ahead ofintermediate image Z2. Due to the fact that the aperture stop ispositioned before the second intermediate image Z2, there is at leastone intermediate image between aperture stop B and image plane 102.

Data for projection objective 1600 is presented in Table 11A and Table11B below. Table 11A presents optical data, while Table 11B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 11A and Table 11B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S10; mirror 2 corresponds tomirror S20; mirror 3 corresponds to mirror S50; mirror 4 corresponds tomirror S60; mirror 5 corresponds to mirror S70; mirror 6 corresponds tomirror S80; mirror 7 corresponds to mirror S30; mirror 8 corresponds tomirror S40; mirror 9 corresponds to mirror SK1; and mirror 10corresponds to mirror SK2.

TABLE 11A Surface Radius Thickness Mode Object INFINITY 808.072 Mirror 112007.16 −708.072 REFL STOP INFINITY 0.000 Mirror 2 1319.376 769.858REFL Mirror 3 433.361 −403.578 REFL Mirror 4 987.208 756.549 REFL Mirror5 −693.043 −152.971 REFL Mirror 6 −376.637 770.120 REFL Mirror 7 772.539−617.149 REFL Mirror 8 734.604 1245.295 REFL Mirror 9 −1353.169 −488.680REFL Mirror 10 976.954 528.680 REFL Image INFINITY 0.000

TABLE 11B Surface K A B C D Mirror 1 0.00000E+00 9.27937E−10−4.60321E−15 1.33022E−20 −1.46239E−25 Mirror 2 0.00000E+00 −1.48167E−10−6.18894E−16 −1.75227E−21 −8.39234E−26 Mirror 3 0.00000E+00 −1.73010E−09−1.18347E−14 9.68679E−20 −9.07327E−25 Mirror 4 0.00000E+00 −6.37553E−11−1.11337E−16 −1.06013E−22 2.52238E−29 Mirror 5 0.00000E+00 6.33779E−10−6.54703E−16 3.63365E−21 −5.36932E−27 Mirror 6 0.00000E+00 6.43612E−09−5.82502E−14 1.35839E−18 −2.25462E−23 Mirror 7 0.00000E+00 3.09804E−091.48684E−14 −4.03834E−19 −5.72817E−24 Mirror 8 0.00000E+00 6.55194E−111.29992E−16 2.37143E−22 4.46073E−28 Mirror 9 0.00000E+00 6.94725E−117.74511E−17 2.33861E−22 9.32544E−29 Mirror 10 0.00000E+00 −1.35922E−10−3.07250E−17 1.86948E−22 2.92915E−28 Surface E F G H J Mirror 11.39879E−30 −1.37935E−36 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 23.00921E−30 −3.04597E−35 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 3−2.20201E−29 2.31377E−34 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 4−8.15911E−34 2.59261E−39 −6.08607E−45 0.00000E+00 0.00000E+00 Mirror 56.45614E−33 −1.77221E−38 5.08599E−44 0.00000E+00 0.00000E+00 Mirror 63.31937E−28 −3.44267E−33 1.68365E−38 0.00000E+00 0.00000E+00 Mirror 7−1.99674E−28 3.88481E−33 −3.50397E−38 0.00000E+00 0.00000E+00 Mirror 83.95152E−34 3.88746E−39 −9.08040E−45 2.70091E−50 0.00000E+00 Mirror 98.50266E−34 −1.88020E−40 4.25518E−46 4.36378E−51 0.00000E+00 Mirror 10−3.23938E−34 1.34899E−39 −3.15465E−45 6.54274E−51 0.00000E+00

Referring to FIG. 17, an embodiment of a projection objective 1700includes ten mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1, andSK2, and has an image-side numerical aperture of 0.75 and an operatingwavelength of 13.5 nm. Mirrors S10, S20, S30, S40, S50, S60, S70, S80,SK1, and SK2 are all aspherical mirrors. Projection objective 1700images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 11 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is2,511 mm.

Projection objective 1700 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 29.75 mm.The image-side field length, d_(y), is 2 mm. Image-side W_(rms) is 0.024λ. Image-side field curvature is 3 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S10 is a convexmirror; mirror S20 is a concave mirror; mirror S50 is a convex mirror;mirror S60 is a concave mirror; mirror S70 is a concave mirror; mirrorS80 is a convex mirror; mirror S30 is a convex mirror; mirror S40 is aconcave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror.

Mirrors S30, S40, S70, SK1, and SK2 include openings. Mirrors S10, S20,S50, S60, and S80 do not include openings. The resulting obscurationradius that provides a field-independent obscuration is 55% of theaperture radius.

The image-side free working distance is 40 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S10, S20, S30, S40, S50, S60,S70, S80, SK1, and SK2 of a chief ray of a central field point is 32.5°.The maximum angle of incidence of any ray on mirrors S10, S20, S30, S40,S50, S60, S70, S80, SK1, and SK2 is 45.1°. The maximum range of incidentangles on any of mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1,and SK2 is 28.9°.

The size of the largest mirror in meridional section is 933 mm. The sizeof the largest mirror in the x-direction is 1028 mm.

The mirrors are arranged so that projection objective 1700 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1700 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop. At least one of the pupil planes isaccessible for positioning an obscuration stop. For example, anobscuration stop can be positioned at mirror S20.

First partial objective 1010 has a total of six mirrors: mirror S10,mirror S20, mirror S50, mirror S60, mirror S70, and mirror S80. Firstpartial objective 1010 forms an intermediate image Z1 in a positionbetween mirrors S40 and S70, which may be at or near either or bothmirrors. Second partial objective 1020 has a total of two mirrors:mirror S30, and mirror S40. Second partial objective 1020 forms anintermediate image Z2 at or near the position of mirror S30. Thirdpartial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image at or near theposition of image plane 102.

The embodiment shown is a pupil-obscurated system with at least onemirror with an opening for the passage of a bundle of rays, whereaperture stop B, positioned near mirror S20, is positioned ahead ofintermediate image Z2. Due to the fact that the aperture stop ispositioned before the second intermediate image Z2, there is at leastone intermediate image between aperture stop B and image plane 102.

Data for projection objective 1700 is presented in Table 12A and Table12B below. Table 12A presents optical data, while Table 12B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 12A and Table 12B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S10; mirror 2 corresponds tomirror S20; mirror 3 corresponds to mirror S50; mirror 4 corresponds tomirror S60; mirror 5 corresponds to mirror S70; mirror 6 corresponds tomirror S80; mirror 7 corresponds to mirror S30; mirror 8 corresponds tomirror S40; mirror 9 corresponds to mirror SK1; and mirror 10corresponds to mirror SK2.

TABLE 12A Surface Radius Thickness Mode Object INFINITY 800.266 Mirror 110314.848 −700.266 REFL STOP INFINITY 0.000 Mirror 2 1313.221 772.471REFL Mirror 3 435.263 −403.381 REFL Mirror 4 987.208 756.370 REFL Mirror5 −693.635 −152.988 REFL Mirror 6 −376.671 770.162 REFL Mirror 7 773.821−617.174 REFL Mirror 8 734.569 1245.278 REFL Mirror 9 −1353.223 −488.675REFL Mirror 10 976.962 528.674 REFL Image INFINITY 0.000

TABLE 12B Surface K A B C D Mirror 1 0.00000E+00 9.53114E−10−4.86644E−15 1.31711E−20 −1.00791E−25 Mirror 2 0.00000E+00 −1.47585E−10−6.60664E−16 −1.36568E−21 −4.71682E−26 Mirror 3 0.00000E+00 −1.70365E−09−1.16839E−14 9.85514E−20 −9.70081E−25 Mirror 4 0.00000E+00 −6.35387E−11−1.10979E−16 −1.03841E−22 2.37479E−29 Mirror 5 0.00000E+00 6.32087E−10−6.50351E−16 3.64943E−21 −5.41639E−27 Mirror 6 0.00000E+00 6.40969E−09−5.76722E−14 1.35569E−18 −2.25614E−23 Mirror 7 0.00000E+00 3.10697E−091.51614E−14 −4.09300E−19 −6.19233E−24 Mirror 8 0.00000E+00 6.56531E−111.29850E−16 2.37674E−22 4.38690E−28 Mirror 9 0.00000E+00 6.93646E−117.77340E−17 2.35663E−22 8.87991E−29 Mirror 10 0.00000E+00 −1.36095E−10−2.99886E−17 1.86689E−22 2.94132E−28 Surface E F G H J Mirror 13.35912E−31 8.78178E−36 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 21.70095E−30 −1.74271E−35 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 3−1.98157E−29 2.10542E−34 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 4−7.95278E−34 2.56682E−39 −6.07013E−45 0.00000E+00 0.00000E+00 Mirror 56.29468E−33 −1.72403E−38 5.01025E−44 0.00000E+00 0.00000E+00 Mirror 63.33377E−28 −3.47620E−33 1.70289E−38 0.00000E+00 0.00000E+00 Mirror 7−7.67239E−29 −2.04991E−33 6.19397E−38 0.00000E+00 0.00000E+00 Mirror 84.29719E−34 3.75714E−39 −8.71022E−45 2.66200E−50 0.00000E+00 Mirror 98.17352E−34 1.07822E−41 1.12329E−47 4.63290E−51 0.00000E+00 Mirror 10−3.16654E−34 1.18038E−39 −2.51249E−45 5.75859E−51 0.00000E+00

Referring to FIG. 18, an embodiment of a projection objective 1800includes ten mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1, andSK2, and has an image-side numerical aperture of 0.7 and an operatingwavelength of 13.5 nm. Mirrors S10, S20, S30, S40, S50, S60, S70, S80,SK1, and SK2 are all aspherical mirrors. Projection objective 1800images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 12 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is2,494 mm.

Projection objective 1800 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 17.15 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.018λ. Image-side field curvature is less than 1 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S10 is a convexmirror; mirror S20 is a concave mirror; mirror S50 is a concave mirror;mirror S60 is a convex mirror; mirror S70 is a convex mirror; mirror S80is a concave mirror; mirror S30 is a convex mirror; mirror S40 is aconcave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror.

Mirrors S30, S40, SK1, and SK2 include openings. Mirrors S10, S20, S50,S60, S70, and S80 do not include openings. The resulting obscurationradius that provides a field-independent obscuration is 26% of theaperture radius.

The image-side free working distance is 40 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S10, S20, S30, S40, S50, S60,S70, S80, SK1, and SK2 of a chief ray of a central field point is 32.7°.The maximum angle of incidence of any ray on mirrors S10, S20, S30, S40,S50, S60, S70, S80, SK1, and SK2 is 42.3°. The maximum range of incidentangles on any of mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1,and SK2 is 18.8°.

The size of the largest mirror in meridional section is 858 mm. The sizeof the largest mirror in the x-direction is 891 mm.

The mirrors are arranged so that projection objective 1800 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1800 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of six mirrors: mirror S10,mirror S20, mirror S50, mirror S60, mirror S70, and mirror S80. Firstpartial objective 1010 forms an intermediate image Z1 in a position ator near mirror S40. Second partial objective 1020 has a total of twomirrors: mirror S30, and mirror S40. Second partial objective 1020 formsan intermediate image Z2 at a position between mirrors S30 and SK2.Third partial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image at or near theposition of image plane 102.

Embodiments shown in FIGS. 11-18 include microlithography projectionobjectives where the first partial objective does not include a mirrorhaving an opening for the passage of a bundle of rays, i.e., none of themirrors are perforated. In addition, the projection objectives include asecond partial objective having no mirror without an opening for thepassage of a bundle of rays. The geometrical distance between the firstand second partial objectives is generally at least 10% of the length,L, from object plane 103 to image plane 102. The distance between thefirst and second partial objectives is the distance between a vertex ofa mirror in the first partial objective that is positioned closest tothe image plane and a vertex of a mirror in the second partial objectivethat is positioned closest to the object plane. The mirror in the secondpartial objective that is positioned closest to the object plane is alsoreferred to as the closest-to-reticle mirror of the second partialobjective, and the mirror in the first partial objective that is closestto the image plane is referred to as the closest-to-substrate mirror ofthe first partial objective.

In the embodiment shown in FIG. 18, the geometrical distance between thefirst partial objective and the second partial objective corresponds toa distance between a vertex V70 of mirror S70 and a vertex V40 of mirrorS40, measured along axis HA. In this embodiment, the distance betweenthe two partial objectives is negative, because the two objectivesoverlap in their spatial arrangement, i.e., mirror S70 is positionedinside the space of the second partial objective.

An arrangement of this type may have the advantage that in embodimentswhere the closest-to-reticle mirror of the second partial objective ispositioned near to the closest-to-substrate mirror of the first partialobjective, the inner ring field radius, and therefore the obscuration,can be kept relatively small.

Further, embodiments shown in FIGS. 11-14, 15A, and 18, as well as otherembodiments presented infra include a negative back-focus width of theentry pupil. The principal rays of the different field points aredivergent as they approach the objective in the direction of lightpropagation, i.e., in a direction starting from the object plane. Inrelation to the light path from a light source of an illumination systemto the object plane where a reticle is located, the entrance pupil ofthe projection objective is positioned in front of the object plane.

Data for projection objective 1800 is presented in Table 13A and Table13B below. Table 13A presents optical data, while Table 13B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 13A and Table 13B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S10; mirror 2 corresponds tomirror S20; mirror 3 corresponds to mirror S50; mirror 4 corresponds tomirror S60; mirror 5 corresponds to mirror S70; mirror 6 corresponds tomirror S80; mirror 7 corresponds to mirror S30; mirror 8 corresponds tomirror S40; mirror 9 corresponds to mirror SK1; and mirror 10corresponds to mirror SK2.

TABLE 13A Surface Radius Thickness Mode Object INFINITY 576.457 Mirror 1743.152 −443.481 REFL Mirror 2 1348.018 992.889 REFL Mirror 3 −1386.925−349.408 REFL Mirror 4 −1014.795 496.732 REFL Mirror 5 324.055 −856.578REFL Mirror 6 941.81 1510.551 REFL STOP INFINITY 0.000 Mirror 7 2311.955−670.058 REFL Mirror 8 862.319 1196.518 REFL Mirror 9 −1133.435 −426.460REFL Mirror 10 831.304 466.461 REFL Image INFINITY 0.000

TABLE 13B Surface K A B C D Mirror 1 0.00000E+00 −1.74588E−095.73560E−15 −2.18120E−20 8.88355E−26 Mirror 2 0.00000E+00 −8.27033E−11−3.72143E−17 6.51400E−24 5.62567E−30 Mirror 3 0.00000E+00 −8.58288E−123.92829E−18 −4.18276E−24 −1.25792E−29 Mirror 4 0.00000E+00 2.07266E−11−4.52705E−16 −2.17586E−21 −1.01747E−26 Mirror 5 0.00000E+00 4.76733E−09−2.14786E−13 −1.18998E−17 −8.08930E−22 Mirror 6 0.00000E+00 1.65766E−112.69419E−17 5.87911E−24 3.46720E−29 Mirror 7 0.00000E+00 8.89937E−101.82131E−15 7.16217E−21 −5.94918E−25 Mirror 8 0.00000E+00 3.72408E−113.09842E−17 3.10857E−23 4.92719E−29 Mirror 9 0.00000E+00 1.94111E−104.16355E−16 1.11547E−21 4.33879E−27 Mirror 10 0.00000E+00 −1.69879E−102.55525E−16 6.73274E−22 −2.01071E−28 Surface E F G H J Mirror 1−1.89149E−31 2.05598E−37 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 20.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 38.61573E−36 5.91202E−42 −2.37686E−48 5.37118E−55 0.00000E+00 Mirror 43.23938E−32 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 52.17082E−25 −2.89803E−29 2.55500E−33 −9.16686E−38 0.00000E+00 Mirror 6−1.13782E−35 1.27000E−39 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 7−2.13013E−29 5.53859E−34 −1.47815E−38 1.00232E−43 0.00000E+00 Mirror 81.90775E−35 1.35114E−40 −5.54544E−47 2.44701E−52 0.00000E+00 Mirror 9−5.57552E−34 3.06849E−38 1.07483E−43 −3.56612E−49 0.00000E+00 Mirror 106.55890E−33 −1.22949E−38 2.98699E−44 2.63597E−50 0.00000E+00

Referring to FIG. 19, an embodiment of a projection objective 1900includes ten mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1, andSK2, and has an image-side numerical aperture of 0.72 and an operatingwavelength of 13.5 nm. Mirrors S10, S20, S30, S40, S50, S60, S70, S80,SK1, and SK2 are all aspherical mirrors. Projection objective 1900images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 12 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is2,500 mm.

Projection objective 1900 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 15.125mm. The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is0.041 λ. Image-side field curvature is 4 nm.

The shape of the mirrors in the order of the radiation path from objectplane 103 to image plane 102 is as follows: mirror S10 is a convexmirror; mirror S20 is a concave mirror; mirror S50 is a convex mirror;mirror S60 is a concave mirror; mirror S70 is a convex mirror; mirrorS80 is a concave mirror; mirror S30 is a convex mirror; mirror S40 is aconcave mirror; mirror SK1 is a concave mirror; and mirror SK2 is aconcave mirror. The radius of curvature of mirror S10 is large enough sothat mirror S10 can be replaced with a planar mirror, or a concavemirror having a similarly large radius of curvature.

Mirrors S30, S40, SK1, and SK2 include openings. Mirrors S10, S20, S50,S60, S70 and S80 do not include openings. The resulting obscurationradius that provides a field-independent obscuration is 27% of theaperture radius.

The image-side free working distance is 40 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S10, S20, S30, S40, S50, S60,S70, S80, SK1, and SK2 of a chief ray of a central field point is 20.0°.The maximum angle of incidence of any ray on mirrors S10, S20, S30, S40,S50, S60, S70, S80, SK1, and SK2 is 27.7°. The maximum range of incidentangles on any of mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1,and SK2 is 20.9°.

The size of the largest mirror in meridional section is 884 mm. The sizeof the largest mirror in the x-direction is 927 mm.

The mirrors are arranged so that projection objective 1900 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 1900 produces four pupil planes and threeintermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop. At least one of the pupil planes isaccessible for positioning an obscuration stop. For example, anobscuration stop can be positioned on mirror S20.

First partial objective 1010 has a total of six mirrors: mirror S10,mirror S20, mirror S50, mirror S60, mirror S70, and mirror S80. Firstpartial objective 1010 forms a first intermediate image Z3 in a positionbetween mirrors S60 and S70. A second intermediate image Z1 is alsoformed, in a position at or near the position of mirror S40. The Z1image is demagnified 2.78×. Second partial objective 1020 has a total oftwo mirrors: mirror S30, and mirror S40. Second partial objective 1020forms an intermediate image Z2 at or near the position of mirror S30.The Z2 image is demagnified 1.29×. Third partial objective 1030 has atotal of two mirrors: mirror SK1, and mirror SK2. Third partialobjective 1030 forms an image at or near the position of image plane102. This image is demagnified 2.24×.

In this and successive embodiments, by providing a third intermediateimage, the cross-sections of the ray bundles, and therefore the utilizedmirror surface areas, can be kept relatively small. Further, in thisembodiment, the angles of incidence of the principal ray of the centralfield point of the field in the field plane are made particularly small.The obscuration in the pupil is only 10% of the surface.

An aperture stop B is positioned near mirror S20.

Data for projection objective 1900 is presented in Table 14A and Table14B below. Table 14A presents optical data, while Table 14B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 14A and Table 14B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S10; mirror 2 corresponds tomirror S20; mirror 3 corresponds to mirror S50; mirror 4 corresponds tomirror S60; mirror 5 corresponds to mirror S70; mirror 6 corresponds tomirror S80; mirror 7 corresponds to mirror S30; mirror 8 corresponds tomirror S40; mirror 9 corresponds to mirror SK1; and mirror 10corresponds to mirror SK2.

TABLE 14A Surface Radius Thickness Mode Object INFINITY 565.102 Mirror 155533.824 −465.102 REFL STOP INFINITY 0.000 Mirror 2 852.374 542.952REFL Mirror 3 281.088 −498.503 REFL Mirror 4 759.16 966.921 REFL Mirror5 309.453 −386.183 REFL Mirror 6 515.051 1141.014 REFL Mirror 7 1674.294−583.849 REFL Mirror 8 758.67 1177.650 REFL Mirror 9 −1322.155 −496.668REFL Mirror 10 927.879 536.666 REFL Image INFINITY 0.000

TABLE 14B Surface K A B C D E F G Mirror 1 0.00000E+00 1.52016E−09−3.52459E−14 6.75945E−19 −9.26171E−24 0.00000E+00 0.00000E+000.00000E+00 Mirror 2 0.00000E+00 1.08280E−10 −6.34141E−15 5.18470E−19−1.66660E−23 0.00000E+00 0.00000E+00 0.00000E+00 Mirror 3 0.00000E+00−5.96955E−09 1.74672E−13 −6.30562E−19 1.33871E−22 −2.49248E−280.00000E+00 0.00000E+00 Mirror 4 0.00000E+00 −1.08435E−11 −1.00947E−168.75041E−22 −3.90330E−27 8.80258E−33 0.00000E+00 0.00000E+00 Mirror 50.00000E+00 −2.51202E−09 7.56313E−12 −6.05145E−16 6.70343E−200.00000E+00 0.00000E+00 0.00000E+00 Mirror 6 0.00000E+00 −2.60613E−10−1.98309E−16 −1.19381E−21 2.15204E−27 0.00000E+00 0.00000E+000.00000E+00 Mirror 7 0.00000E+00 6.30349E−10 −3.39796E−15 1.21242E−19−1.06347E−24 −2.29594E−29 0.00000E+00 0.00000E+00 Mirror 8 0.00000E+001.23547E−10 2.57281E−16 4.94742E−22 7.10013E−28 2.49635E−33 0.00000E+000.00000E+00 Mirror 9 0.00000E+00 1.05621E−10 1.30680E−17 4.34693E−22−3.96448E−28 1.80389E−33 0.00000E+00 0.00000E+00 Mirror 10 0.00000E+00−2.03140E−10 −2.32499E−17 2.98416E−22 −2.49605E−28 8.14302E−340.00000E+00 0.00000E+00

Referring to FIG. 20, an embodiment of a projection objective 2000includes ten mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1, andSK2, and has an image-side numerical aperture of 0.7 at an operatingwavelength of 13.5 nm. Mirrors S10, S20, S30, S40, S50, S60, S70, S80,SK1, and SK2 are all aspherical mirrors. Projection objective 2000images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 12 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is2,246 mm.

Projection objective 2000 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 16.25 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.3λ. Image-side field curvature is 27 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S10 is aconcave mirror; mirror S20 is a convex mirror; mirror S50 is a concavemirror; mirror S60 is a concave mirror; mirror S70 is a convex mirror;mirror S80 is a concave mirror; mirror S30 is a convex mirror; mirrorS40 is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2is a concave mirror.

Mirrors S30, S40, SK1, and SK2 include openings. Mirrors S10, S20, S50,S60, S70 and S80 do not include openings. The resulting obscurationradius that provides a field-independent obscuration is 28% of theaperture radius.

The image-side free working distance is 40 mm. The object-side freeworking distance is 468 mm.

The maximum angle of incidence on mirrors S10, S20, S30, S40, S50, S60,S70, S80, SK1, and SK2 of a chief ray of a central field point is 35.3°.The maximum angle of incidence of any ray on mirrors S10, S20, S30, S40,S50, S60, S70, S80, SK1, and SK2 is 42.4°. The maximum range of incidentangles on any of mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1,and SK2 is 18.9°.

The size of the largest mirror in meridional section is 836 mm. The sizeof the largest mirror in the x-direction is 834 mm.

The mirrors are arranged so that projection objective 2000 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 2000 produces four pupil planes and threeintermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of six mirrors: mirror S10,mirror S20, mirror S50, mirror S60, mirror S70, and mirror S80. Firstpartial objective 1010 forms a first intermediate image Z3 in a positionbetween mirrors S60 and S70. A second intermediate image Z1 is alsoformed, in a position at or near the position of mirror S40. Secondpartial objective 1020 has a total of two mirrors: mirror S30, andmirror S40. Second partial objective 1020 forms an intermediate image Z2at or near the position of mirror S30. Third partial objective 1030 hasa total of two mirrors: mirror SK1, and mirror SK2. Third partialobjective 1030 forms an image at or near the position of image plane102.

An aperture stop B is positioned near mirror S30.

Data for projection objective 2000 is presented in Table 15A and Table15B below. Table 15A presents optical data, while Table 15B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 15A and Table 15B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S10; mirror 2 corresponds tomirror S20; mirror 3 corresponds to mirror S50; mirror 4 corresponds tomirror S60; mirror 5 corresponds to mirror S70; mirror 6 corresponds tomirror S80; mirror 7 corresponds to mirror S30; mirror 8 corresponds tomirror S40; mirror 9 corresponds to mirror SK1; and mirror 10corresponds to mirror SK2.

TABLE 15A Surface Radius Thickness Mode Object INFINITY 559.181 Mirror 1−245.847 −91.621 REFL Mirror 2 −106.241 409.943 REFL Mirror 3 −797.047−329.100 REFL Mirror 4 1288.083 544.097 REFL Mirror 5 471.444 −352.779REFL Mirror 6 391.18 895.651 REFL STOP INFINITY 0.000 Mirror 7 89550.706−575.938 REFL Mirror 8 769.632 1146.221 REFL Mirror 9 −1294.759 −470.344REFL Mirror 10 921.525 510.244 REFL Image INFINITY 0.000

TABLE 15B Surface K A B C D E F G Mirror 1 0.00000E+00 7.66254E−092.77417E−14 1.36582E−18 1.60505E−23 0.00000E+00 0.00000E+00 0.00000E+00Mirror 2 0.00000E+00 7.08392E−07 8.77265E−11 −1.08467E−13 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 Mirror 3 0.00000E+00 3.26115E−103.33584E−16 −5.68189E−21 1.08127E−25 −4.00572E−31 0.00000E+000.00000E+00 Mirror 4 0.00000E+00 2.50220E−10 −4.02328E−15 3.97478E−20−1.61324E−25 2.23312E−31 0.00000E+00 0.00000E+00 Mirror 5 0.00000E+008.20670E−08 8.14545E−12 4.31824E−16 1.12366E−19 0.00000E+00 0.00000E+000.00000E+00 Mirror 6 0.00000E+00 1.46218E−09 2.25940E−14 5.19142E−19−2.84570E−24 3.72190E−28 0.00000E+00 0.00000E+00 Mirror 7 0.00000E+004.23423E−09 −7.06964E−14 9.09880E−19 −9.81546E−24 1.27493E−29−6.38729E−35 0.00000E+00 Mirror 8 0.00000E+00 6.41818E−11 1.25081E−164.78443E−23 1.99269E−27 −5.19669E−33 2.07669E−38 0.00000E+00 Mirror 90.00000E+00 −2.72326E−10 1.27303E−15 −6.33084E−21 2.30570E−26−5.38480E−32 6.82514E−38 0.00000E+00 Mirror 10 0.00000E+00 −2.43581E−10−6.44997E−16 3.73803E−22 1.59378E−27 −2.26603E−32 7.46453E−380.00000E+00

Referring to FIG. 21, an embodiment of a projection objective 2100includes ten mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1, andSK2, and has an image-side numerical aperture of 0.72 at an operatingwavelength of 13.4 nm. Mirrors S10, S20, S30, S40, S50, S60, S70, S80,SK1, and SK2 are all aspherical mirrors. Projection objective 2100images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 12 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is2,800 mm.

Projection objective 2100 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 21.25 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.052λ. Image-side field curvature is 7 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S10 is aconcave mirror; mirror S20 is a convex mirror; mirror S50 is a concavemirror; mirror S60 is a convex mirror; mirror S70 is a convex mirror;mirror S80 is a concave mirror; mirror S30 is a convex mirror; mirrorS40 is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2is a concave mirror.

Mirrors S30, S40, SK1, and SK2 include openings. Mirrors S10, S20, S50,S60, S70 and S80 do not include openings. The resulting obscurationradius that provides a field-independent obscuration is 29% of theaperture radius.

The image-side free working distance is 41 mm. The object-side freeworking distance is 729 mm.

The maximum angle of incidence on mirrors S10, S20, S30, S40, S50, S60,S70, S80, SK1, and SK2 of a chief ray of a central field point is 35.0°.The maximum angle of incidence of any ray on mirrors S10, S20, S30, S40,S50, S60, S70, S80, SK1, and SK2 is 39.6°. The maximum range of incidentangles on any of mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1,and SK2 is 24.5°.

The size of the largest mirror in meridional section is 871 mm. The sizeof the largest mirror in the x-direction is 918 mm.

The mirrors are arranged so that projection objective 2100 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 2500 produces four pupil planes and threeintermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop. At least one of the pupil planes isaccessible for positioning an obscuration stop. For example, anobscuration stop can be positioned on mirror S10.

First partial objective 1010 has a total of six mirrors: mirror S10,mirror S20, mirror S50, mirror S60, mirror S70, and mirror S80. Firstpartial objective 1010 forms a first intermediate image Z3 in a positionbetween mirrors S20 and S50. A second intermediate image Z1 is alsoformed, in a position at or near the position of mirror S40. Secondpartial objective 1020 has a total of two mirrors: mirror S30, andmirror S40. Second partial objective 1020 forms an intermediate image Z2at or near the position of mirror S30. Third partial objective 1030 hasa total of two mirrors: mirror SK1, and mirror SK2. Third partialobjective 1030 forms an image at or near the position of image plane102.

An aperture stop B is positioned near mirror S10.

The systems shown in FIGS. 20 and 21 include six or more mirrors, whereat least one mirror includes no opening for the passage of a bundle ofrays, and where that mirror is also positioned at the shortest distancefrom object plane 103, relative to the other mirrors, the distance beinglarger than 15% of the lengthwise dimension of the objective. With anobject-side free working distance of this magnitude, a sufficient amountof space is provided to accommodate mechanical components, e.g., areticle stage, and optical filter elements that have field-dependenteffects and therefore have to be arranged near a field plane, and likecomponents.

In the embodiments shown in FIGS. 20 and 21, the mirror that has noopening and, measured along the axis HA, has the shortest distance fromthe object plane, is mirror S20. The distance of mirror S20 from objectplane 103 is measured as the distance from vertex V20 of mirror S20 fromobject plane 103.

Data for projection objective 2100 is presented in Table 16A and Table16B below. Table 16A presents optical data, while Table 16B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 16A and Table 16B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S10; mirror 2 corresponds tomirror S20; mirror 3 corresponds to mirror S50; mirror 4 corresponds tomirror S60; mirror 5 corresponds to mirror S70; mirror 6 corresponds tomirror S80; mirror 7 corresponds to mirror S30; mirror 8 corresponds tomirror S40; mirror 9 corresponds to mirror SK1; and mirror 10corresponds to mirror SK2.

TABLE 16A Surface Radius Thickness Mode Object INFINITY 984.370 STOPINFINITY 0.000 Mirror 1 −487.824 −255.596 REFL Mirror 2 −203.99 720.214REFL Mirror 3 −618.943 −342.547 REFL Mirror 4 −467.367 522.697 REFLMirror 5 1517.781 −594.768 REFL Mirror 6 691.924 1170.936 REFL Mirror 72075.314 −583.106 REFL Mirror 8 756.671 1136.329 REFL Mirror 9 −1247.404−502.341 REFL Mirror 10 947.118 543.813 REFL Image INFINITY 0.000

TABLE 16B Surface K A B C D E F G Mirror 1 0.00000E+00 3.07073E−10−2.63762E−14 −4.75987E−19 1.15793E−22 −2.70203E−26 1.70913E−300.00000E+00 Mirror 2 0.00000E+00 −5.92526E−09 −1.01630E−12 3.61436E−16−1.06065E−19 1.63883E−23 −1.10394E−27 0.00000E+00 Mirror 3 0.00000E+001.01014E−10 −8.68729E−16 4.12943E−21 −7.94689E−27 1.74105E−331.29251E−38 0.00000E+00 Mirror 4 0.00000E+00 1.63695E−09 3.55194E−14−6.73526E−19 7.84526E−24 −4.94145E−29 1.32806E−34 0.00000E+00 Mirror 50.00000E+00 3.47124E−08 1.00844E−12 4.12785E−17 6.94133E−21 −6.19939E−259.05297E−29 0.00000E+00 Mirror 6 0.00000E+00 2.82522E−11 1.38881E−16−6.42306E−23 8.71534E−27 −1.78347E−31 7.69324E−37 0.00000E+00 Mirror 70.00000E+00 −2.11518E−10 −4.61053E−15 −1.12662E−19 8.47783E−26−5.55624E−30 −2.20618E−34 0.00000E+00 Mirror 8 0.00000E+00 6.09426E−118.83052E−17 8.08906E−23 2.92953E−29 2.28833E−34 −1.14558E−40 0.00000E+00Mirror 9 0.00000E+00 7.30445E−11 1.71628E−16 3.00636E−22 2.96880E−281.02229E−33 1.04271E−39 0.00000E+00 Mirror 10 0.00000E+00 −1.78072E−10−6.22611E−17 3.97686E−22 5.02383E−28 −2.14813E−33 3.31869E−390.00000E+00

FIG. 22 shows an expanded view of an embodiment of a second partialobjective 1020 and a third partial objective 1030. Second partialobjective 1020 includes convex mirror S105 and concave mirror S110.Third partial objective includes concave mirror S120 and concave mirrorS130. An intermediate image Z2 is formed at or near the position ofmirror S105 by second partial objective 1020. The intermediate image ator near the location of mirror S105 leads to a surface obscuration ofabout 10% of the pupil of the projection objective.

FIG. 23 shows an expanded view of another embodiment of a second partialobjective 1020 and a third partial objective 1030. Second partialobjective 1020 includes convex mirror S105 and concave mirror S110.Third partial objective includes concave mirror S120 and concave mirrorS130. In this embodiment, surface obscuration of the pupil of theprojection objective is about 8% as a result of positioning intermediateimage Z2 between mirrors S105 and S130. Along the light path's mirrorsequence from the object plane to the image plane, these mirrors are,respectively, the fourth-from-last mirror and the last mirror from theobject plane. The mirrors are selected so that the condition d₁/d₂=z₁/z₂ is met, where d₁ is the diameter of mirror S130, d₂ is thediameter of mirror S105, z₁ is the distance from intermediate image Z2to the surface of mirror S130, and z₂ is the distance from intermediateimage Z2 to the surface of mirror S105.

FIG. 24 shows an expanded view of an embodiment of a third partialobjective 1030 in which a Mangin mirror S140 is used in place of mirrorS120 in FIG. 23, for example. A system with a Mangin mirror has theadvantage that the space required for mounting the mirror is madeavailable by the optical element E140 through which the light has topass in order to reflect from mirror S140, which is located on a backsurface of element E140. As a result of this configuration, mirror S140can be positioned very close to image plane 102 without compromisingstability.

Referring to FIG. 25, an embodiment of a projection objective 2500includes ten mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1, andSK2, and has an image-side numerical aperture of 0.7 at an operatingwavelength of 193.3 nm. Mirrors S10, S20, S30, S40, S50, S60, S70, S80,SK1, and SK2 are all aspherical mirrors. Projection objective 2500images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 100 nm. Theoptical axis in relation to which the projection objective isrotationally symmetric is identified as HA, and the overall length ofthe system from object plane 103 to the image plane 102, the lengthwisedimension, L, is 2,500 mm.

Projection objective 2500 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 18.75 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.023λ. Image-side field curvature is 59 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S10 is aconvex mirror; mirror S20 is a concave mirror; mirror S50 is a concavemirror; mirror S60 is a convex mirror; mirror S70 is a convex mirror;mirror S80 is a concave mirror; mirror S30 is a convex mirror; mirrorS40 is a concave mirror; mirror SK1 is a concave mirror; and mirror SK2is a concave mirror. Mirror SK1 is a Mangin mirror, as discussedpreviously.

Mirrors S30, S40, SK1, and SK2 include openings. Mirrors S10, S20, S50,S60, S70 and S80 do not include openings. The resulting obscurationradius that provides a field-independent obscuration is 28% of theaperture radius.

The image-side free working distance is 10 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S10, S20, S30, S40, S50, S60,S70, S80, SK1, and SK2 of a chief ray of a central field point is 37.6°.The maximum angle of incidence of any ray on mirrors S10, S20, S30, S40,S50, S60, S70, S80, SK1, and SK2 is 49.4°. The maximum range of incidentangles on any of mirrors S10, S20, S30, S40, S50, S60, S70, S80, SK1,and SK2 is 22.4°.

The size of the largest mirror in meridional section is 889 mm. The sizeof the largest mirror in the x-direction is 883 mm.

The mirrors are arranged so that projection objective 2500 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 2500 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of six mirrors: mirror S10,mirror S20, mirror S50, mirror S60, mirror S70, and mirror S80. Firstpartial objective 1010 forms a first intermediate image Z1 in a positionat or near mirror S40. Second partial objective 1020 has a total of twomirrors: mirror S30, and mirror S40. Second partial objective 1020 formsan intermediate image Z2 at or near the position of mirror S30. Thirdpartial objective 1030 has a total of two mirrors: mirror SK1, andmirror SK2. Third partial objective 1030 forms an image at or near theposition of image plane 102.

Data for projection objective 2500 is presented in Table 17A and Table17B below. Table 17A presents optical data, while Table 17B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 17A and Table 17B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S10; mirror 2 corresponds tomirror S20; mirror 3 corresponds to mirror S50; mirror 4 corresponds tomirror S60; mirror 5 corresponds to mirror S70; mirror 6 corresponds tomirror S80; mirror 7 corresponds to mirror S30; mirror 8 corresponds tomirror S40; mirror 9 corresponds to mirror SK1; and mirror 10corresponds to mirror SK2.

To provide a realization of low angles of incidence in a high aperturesystem, it can be advantageous if the second mirror in the light path ofthe first partial objective is a concave mirror. This may lead torelatively low angles of incidence on all mirrors. Further, this designchoice can facilitate the production of mirror coatings because lowangles of incidence reduce the need for providing a coating with alateral thickness variation of the mirror surface. Instead, the coatingthickness can be relatively constant over the mirror surface. Inaddition, lower angles of incidence can result in higher reflectivityfrom the mirror surface.

TABLE 17A Surface Radius Thickness Mode n Object INFINITY 533.185 Mirror1 998.875 −433.185 REFL Mirror 2 1507.19 966.402 REFL Mirror 3 −1186.286−333.216 REFL Mirror 4 −774.298 492.401 REFL Mirror 5 345.555 −796.615REFL Mirror 6 875.806 1462.434 REFL STOP INFINITY 0.000 Mirror 7 2012.09−663.855 REFL Mirror 8 868.41 1161.917 REFL Sphere −1142.612 99.999 REFR1.560491 Mirror 9 −1173.131 −99.999 REFL 1.560491 Sphere −1142.612−398.063 REFR Mirror 10 864.134 398.063 REFL Sphere −1142.612 99.999REFR 1.560491 Asphere −1173.131 9.950 REFR Image INFINITY 0.000

TABLE 17B Surface K A B C D E F G Mirror 1 0.00000E+00 −4.63661E−101.49173E−15 1.17129E−20 −1.03763E−25 −3.90507E−32 0.00000E+000.00000E+00 Mirror 2 0.00000E+00 −6.57662E−11 −4.99638E−17 4.57647E−23−5.45358E−30 −1.74383E−34 0.00000E+00 0.00000E+00 Mirror 3 0.00000E+001.36485E−11 −1.81657E−17 5.69451E−23 −7.91336E−29 9.23378E−360.00000E+00 0.00000E+00 Mirror 4 0.00000E+00 4.34663E−10 −1.84433E−151.91302E−20 −1.21633E−25 3.53832E−31 0.00000E+00 0.00000E+00 Mirror 50.00000E+00 −2.90145E−10 −4.30363E−14 2.45843E−17 −1.57578E−212.19218E−25 0.00000E+00 0.00000E+00 Mirror 6 0.00000E+00 −8.22539E−115.31955E−18 −3.31349E−22 3.61420E−28 5.96686E−34 0.00000E+00 0.00000E+00Mirror 7 0.00000E+00 8.95414E−10 0.00000E+00 0.00000E+00 9.11424E−25−4.57429E−30 0.00000E+00 0.00000E+00 Mirror 8 0.00000E+00 6.40715E−117.25579E−17 1.14913E−22 2.64566E−28 −1.96096E−34 1.92729E−39 0.00000E+00Mirror 9 0.00000E+00 1.11862E−10 9.94515E−17 3.86584E−22 5.06626E−28−1.28846E−33 1.47731E−38 0.00000E+00 Mirror 10 0.00000E+00 −1.92745E−103.60396E−16 2.01867E−22 7.88027E−28 −2.94908E−33 2.20072E−38 0.00000E+00Asphere 0.00000E+00 1.11862E−10 9.94515E−17 3.86584E−22 5.06626E−28−1.28846E−33 1.47731E−38 0.00000E+00

Referring to FIG. 26, an embodiment of a projection objective 2600includes six mirrors S100, S200, S300, S400, S500, and S600, and has animage-side numerical aperture of 0.5 at an operating wavelength of 13.5nm. Mirrors S100, S200, S300, S400, S500, and S600 are all asphericalmirrors. Projection objective 2600 images radiation from object plane103 to image plane 102 with a demagnification ratio of 8× and aresolution of about 17 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,521 mm.

Projection objective 2600 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 9.75 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.028λ. Image-side field curvature is 10 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S100 is aconcave mirror; mirror S200 is a concave mirror; mirror S300 is a convexmirror; mirror S400 is a concave mirror; mirror S500 is a convex mirror;and mirror S600 is a concave mirror. The use of a concave second mirrorS200 provides for relatively low angles of incidence in this embodiment.

Mirrors S500 and S600 include openings. Mirrors S100, S200, S300, andS400 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 25% of the aperture radius.

The image-side free working distance is 39 mm. The object-side freeworking distance is 158 mm.

The maximum angle of incidence on mirrors S100, S200, S300, S400, S500,and S600 of a chief ray of a central field point is 12.3°. The maximumangle of incidence of any ray on mirrors S100, S200, S300, S400, S500,and S600 is 16.9°. The maximum range of incident angles on any ofmirrors S100, S200, S300, S400, S500, and S600 is 7.5°.

The size of the largest mirror in meridional section is 675 mm. The sizeof the largest mirror in the x-direction is 687 mm.

The mirrors are arranged so that projection objective 2600 contains twopartial objectives: a first partial objective 1010 and a second partialobjective 1020. Accordingly, projection objective 2600 produces twopupil planes and one intermediate image. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, in the embodiment shown, an obscuration stop AB is positionedbetween mirrors S300 and S400. By positioning the obscuration stop inthis location, a field-independent obscuration of about 25% with a fullyopen aperture is realized.

First partial objective 1010 has a total of four mirrors: mirror S100,mirror S200, mirror S300, and mirror S400. First partial objective 1010forms a first intermediate image Z1 in a position between mirrors S400and S500. Second partial objective 1020 has a total of two mirrors:mirror S500, and mirror S600. Second partial objective 1020 forms animage at or near the position of image plane 102.

An aperture stop B is positioned between mirrors S500 and S600.

When the obscuration stop AB, which defines the inside radius of theilluminated field and thus the obscuration, is arranged between twomirrors, i.e., relatively far from a mirror position, the obscurationstop is passed only once in the light path of the imaging light raybundle, so that no vignetting effects occur. Further, sufficient spacefor the obscuration stop is provided (i.e., the stop is not constrictedby space requirements for mirrors), so that the obscuration stop iseasily interchangeable, since it is not realized by an anti-reflectioncoating on a mirror.

In the embodiment shown, aperture stop B and obscuration stop AB arelocated in two different stop planes that are conjugate to one anotherand are at a distance from each of the mirrors. Aperture stop B ispositioned in stop plane P500 and the obscuration stop lies in stopplane P600. The planes P500 and P600 are conjugate to the entry pupil ofthe projection objective, and lie at the point of intersection of theprincipal ray (i.e., chief ray CR) and axis HA of the objective.

The angles of incidence of the principal ray of the central field pointon all mirrors are smaller than 20° relative to the local surface-normaldirection. The maximum angle of incidence of the principal ray of thecentral field point in the objective occurs on mirror S300 and is 12.3°,as discussed above. As a result of maintaining the angles of incidenceon the mirrors small, a higher reflectivity from the individual mirrorsis realized, and a higher transmissivity for the overall objective isobtained. In particular, the reflectivity for p-polarized components oflight decreases as the angle of incidence increases.

Data for projection objective 2600 is presented in Table 18A and Table18B below. Table 18A presents optical data, while Table 18B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 18A and Table 18B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S100; mirror 2 corresponds tomirror S200; mirror 3 corresponds to mirror S300; mirror 4 correspondsto mirror S400; mirror 5 corresponds to mirror S500; mirror 6corresponds to mirror S600; STOP corresponds to aperture stop B; andImage corresponds to image plane 102.

TABLE 18A Surface Radius Thickness Mode Object INFINITY 670.918 Mirror 1−119254.844 −513.109 REFL Mirror 2 1058.494 657.514 REFL Mirror 3236.520 −352.038 REFL Mirror 4 406.062 1018.792 REFL Mirror 5 2416.511−213.326 REFL STOP INFINITY −406.623 Mirror 6 813.393 659.142 REFL ImageINFINITY 0

TABLE 18B Surface K A B Mirror 1 0.00000E+00 −1.71227E−10 1.21604E−16Mirror 2 0.00000E+00 −3.98375E−11 −5.16759E−17 Mirror 3 0.00000E+002.49910E−09 5.14762E−13 Mirror 4 0.00000E+00 6.84051E−10 5.83113E−15Mirror 5 0.00000E+00 1.05935E−09 2.78882E−15 Mirror 6 0.00000E+002.33770E−11 5.31421E−17 Surface C D E Mirror 1 −1.63049E−21 4.61626E−270.00000E+00 Mirror 2 −1.23197E−22 −2.34001E−28 0.00000E+00 Mirror 3−1.78225E−17 7.40434E−22 0.00000E+00 Mirror 4 5.23435E−20 3.88486E−255.48925E−30 Mirror 5 1.34567E−20 5.03919E−26 8.14921E−31 Mirror 69.34234E−23 1.04943E−28 4.61313E−34

Referring to FIG. 27, an embodiment of a projection objective 2700includes six mirrors S100, S200, S300, S400, S500, and S600, and has animage-side numerical aperture of 0.5 at an operating wavelength of 13.5nm. Mirrors S100, S200, S300, S400, S500, and S600 are all asphericalmirrors. Projection objective 2700 images radiation from object plane103 to image plane 102 with a demagnification ratio of 8× and aresolution of about 17 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,500 mm.

Projection objective 2700 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 12.5 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.02λ. Image-side field curvature is 7 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S100 is aconvex mirror; mirror S200 is a concave mirror; mirror S300 is a convexmirror; mirror S400 is a concave mirror; mirror S500 is a convex mirror;and mirror S600 is a concave mirror.

Mirrors S500 and S600 include openings. Mirrors S100, S200, S300, andS400 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 22% of the aperture radius.

The image-side free working distance is 30 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S100, S200, S300, S400, S500,and S600 of a chief ray of a central field point is 27.4°. The maximumangle of incidence of any ray on mirrors S100, S200, S300, S400, S500,and S600 is 34.9°. The maximum range of incident angles on any ofmirrors S100, S200, S300, S400, S500, and S600 is 15.0°.

The size of the largest mirror in meridional section is 664 mm. The sizeof the largest mirror in the x-direction is 677 mm.

The mirrors are arranged so that projection objective 2700 contains twopartial objectives: a first partial objective 1010 and a second partialobjective 1020. Accordingly, projection objective 2700 produces twopupil planes and one intermediate image. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, in the embodiment shown, an obscuration stop AB is positionedbetween mirrors S300 and S400 in plane P600.

First partial objective 1010 has a total of four mirrors: mirror S100,mirror S200, mirror S300, and mirror S400. First partial objective 1010forms a first intermediate image Z1 in a position between mirrors S400and S500. Second partial objective 1020 has a total of two mirrors:mirror S500, and mirror S600. Second partial objective 1020 forms animage at or near the position of image plane 102.

An aperture stop B is positioned between mirrors S500 and S600 in planeP500.

The embodiments shown in FIGS. 26 and 27 differ from one another intheir ray tracing patterns in the area of mirrors S100 and S200. In theembodiment of FIG. 26, the third mirror S300 is positioned so that theray paths intersect in the area between mirrors S100 and S200. In theembodiment of FIG. 27, the rays do not cross their own paths.

The embodiments of FIGS. 26 and 27 can have the following advantageousproperties. In order to obtain an obscuration that is as small aspossible, the distance from intermediate image Z1 to the geometricallynearest mirror of first partial objective 1010 is less than about 15% ofthe lengthwise dimension of the objective. The geometrically nearestmirror in these embodiments is mirror S300. As in preceding embodiments,the distance from intermediate image Z1 to mirror S300 is determined bythe distance from vertex V300 of mirror S300 to intermediate image Z1along axis HA.

Alternatively, or in addition to, the above property, the goal of asmall obscuration may be further realized by maintaining the distancefrom intermediate image Z1 to the geometrically nearest mirror of secondpartial objective 1020 as less than about 8% of the lengthwise dimensionof the objective. In these embodiments, the geometrically nearest mirrorof second partial objective 1020 is mirror S600. As in precedingembodiments, the distance from intermediate image Z1 to mirror S600 isdetermined by the distance from vertex V600 of mirror S600 tointermediate image Z1 along axis HA.

As a further advantageous measure, the distance between vertex V200 ofmirror S200 and vertex V300 of mirror S300 may be larger than about 18%of the lengthwise dimension of the objective.

As yet another advantageous measure with regard to the embodiments ofFIGS. 26 and 27, the ratio of the diameter D600 of mirror S600 (i.e.,the mirror having the largest diameter in the projection objective) tothe lengthwise dimension of the system is less than 0.9 times as largeas the image-side numerical aperture.

Data for projection objective 2700 is presented in Table 19A and Table19B below. Table 19A presents optical data, while Table 19B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 19A and Table 19B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S100; mirror 2 corresponds tomirror S200; mirror 3 corresponds to mirror S300; mirror 4 correspondsto mirror S400; mirror 5 corresponds to mirror S500; mirror 6corresponds to mirror S600; STOP corresponds to aperture stop B; andImage corresponds to image plane 102.

TABLE 19A Surface Radius Thickness Mode Object INFINITY 294.339 Mirror 1343.317 −194.339 REFL Mirror 2 485.792 754.54 REFL Mirror 3 270.258−275.539 REFL Mirror 4 290.188 890.999 REFL Mirror 5 9383.676  −194.679REFL STOP INFINITY −420.681 Mirror 6 841.549 645.36 REFL Image INFINITY0

TABLE 19B Surface K A B C D E F G Mirror 1 0.00000E+00 −4.96680E−098.07536E−14 −5.21657E−18 1.71166E−22 −3.14607E−27 2.43204E−320.00000E+00 Mirror 2 0.00000E+00 −2.08389E−10 9.04247E−16 −1.82476E−209.83920E−26 −3.32658E−31 0.00000E+00 0.00000E+00 Mirror 3 0.00000E+00−8.58156E−10 −1.09899E−14 1.23347E−16 −9.03339E−20 3.25799E−23−4.65457E−27 0.00000E+00 Mirror 4 0.00000E+00 −3.90441E−10 −7.66964E−158.88342E−20 −3.20552E−23 3.31626E−27 −1.39847E−31 0.00000E+00 Mirror 50.00000E+00 9.99387E−10 2.33248E−15 8.58665E−21 3.37347E−26 3.00073E−313.53144E−37 0.00000E+00 Mirror 6 0.00000E+00 4.04329E−11 7.49328E−171.16246E−22 1.88402E−28 1.78827E−34 9.03324E−40 0.00000E+00

FIG. 28 shows an illumination system 3000 in conjunction with anembodiment of a projection objective 2800. Illumination system 3000includes a light source 3010 and a grating incidence collector. Aspectral filter element 3020 can be configured as a diffractive spectralfilter. In combination with stop 3030 in proximity to an intermediateimage ZQ of the light source, this arrangement permits the exclusion ofundesirable radiation, for example, radiation with wavelengthssignificantly larger than the desired wavelength, from entering the partof the illumination system that lies beyond stop 3030. Arranged in theillumination system along the light path after stop 3030 is araster-type mirror with raster elements or field facets 3040. The fieldfacets separate light ray bundle 3050 emerging from spectral filter 3020into a plurality of individual light ray bundles, each with anassociated secondary light source. The locations of the secondary lightsources are in the vicinity of individual raster elements of a secondraster-type mirror. The raster elements of the second raster-type mirrorare referred to as pupil facets.

Doubly-faceted illumination systems have been disclosed, for example, inU.S. Pat. No. 6,195,201, where the field raster elements or field facetshave the same shape as the field that is to be illuminated in the objectplane, so that the field facets determine the shape of the field in theobject plane. If the field in the object plane has the shape of, forexample, a segment of a circle, then the field facets are likewisesegment-shaped. Alternatively, in some embodiments, the field rasterelements can have a rectangular shape, see for example U.S. Pat. No.6,198,793, where shaping of the field occurs with the help of afield-shaping mirror.

Object plane 3090 into which the field is projected coincides withobject plane 103 of the projection objective. The projection objectiveprojects an image of the field in object plane 103 into a field in imageplane 102. In image plane 102, a substrate with a light-sensitivecoating can be positioned, such as a wafer, for example.

The system shown is distinguished by the entry of principal rays ondivergent paths into the entry pupil of the projection objective thatcoincides with the exit pupil of illumination system 3000. In the lightpath from light source 3010 to object plane 3090, the entry pupil of theprojection objective is positioned in front of object plane 3090.Projection systems having a negative entry pupil are disclosed, forexample, in PCT Patent Application No. WO 2004/010224.

Projection objective 2800 includes eight mirrors S1-S6, SK1, and SK2,and has an image-side numerical aperture of 0.5 at an operatingwavelength of 13.5 nm. Mirrors S1-S6, SK1, and SK2 are all asphericalmirrors. Projection objective 2800 images radiation from object plane103 to image plane 102 with a demagnification ratio of 4× and aresolution of about 17 nm. The optical axis in relation to which theprojection objective is rotationally symmetric is identified as HA, andthe overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,711 mm.

Projection objective 2800 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 13.0 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.044λ. Image-side field curvature is 12 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S1 is aconvex mirror; mirror S2 is a concave mirror; mirror S5 is a convexmirror; mirror S6 is a concave mirror; mirror S3 is a convex mirror;mirror S4 is a concave mirror; mirror SK1 is a concave mirror; andmirror SK2 is a concave mirror.

Mirrors S3, S4, SK1, and SK2 include openings. Mirrors S1, S2, S5, andS6 do not include openings. The resulting obscuration radius thatprovides a field-independent obscuration is 36% of the aperture radius.

The image-side free working distance is 69 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S1-S6, SK1, and SK2 of a chiefray of a central field point is 19.4°. The maximum angle of incidence ofany ray on mirrors S1-S6, SK1, and SK2 is 21.8°. The maximum range ofincident angles on any of mirrors S1-S6, SK1, and SK2 is 15.0°.

The size of the largest mirror in meridional section is 385 mm. The sizeof the largest mirror in the x-direction is 616 mm.

The mirrors in projection objective 2800 are arranged so that projectionobjective 2800 contains three partial objectives: a first partialobjective 1010, a second partial objective 1020, and a third partialobjective 1030. Accordingly, projection objective 2800 produces threepupil planes and two intermediate images. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, in the embodiment shown, an obscuration stop can be positionedbetween mirrors S1 and S2.

First partial objective 1010 has a total of four mirrors: mirror S1,mirror S2, mirror S5, and mirror S6. First partial objective 1010 formsa first intermediate image Z1 in a position between mirrors S6 and S3.Second partial objective 1020 has a total of two mirrors: mirror S3, andmirror S4. Second partial objective 1020 forms a second intermediateimage Z2 at or near the position of mirror S3. Third partial objective1030 has a total of two mirrors: mirror SK1 and mirror SK2. Thirdpartial objective 1030 forms an image at or near the position of imageplane 102.

Referring to FIG. 29, an embodiment of a projection objective 2900includes ten mirrors MIR1-MIR10, and has an image-side numericalaperture of 0.72 at an operating wavelength of 100 nm. MirrorsMIR1-MIR10 are all aspherical mirrors. Projection objective 2900 imagesradiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 49 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is1,374 mm.

Projection objective 2900 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 15.0 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is0.0036 λ. Image-side field curvature is 2 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror MIR1 is aconcave mirror; mirror MIR2 is a concave mirror; mirror MIR3 is a convexmirror; mirror MIR4 is a concave mirror; mirror MIR5 is a concavemirror; mirror MIR6 is a convex mirror; mirror MIR7 is a convex mirror;mirror MIR8 is a concave mirror; mirror MIR9 is a concave mirror; andmirror MIR10 is a concave mirror.

Mirrors MIR7, MIR8, MIR9 and MIR10 include openings. Mirrors MIR1, MIR2,MIR3, MIR4, MIR5 and MIR6 do not include openings. The resultingobscuration radius that provides a field-independent obscuration is 32%of the aperture radius.

The image-side free working distance is 20 mm. The object-side freeworking distance is 50 mm.

The maximum angle of incidence on mirrors MIR1-MIR10 of a chief ray of acentral field point is 48.0°. The maximum angle of incidence of any rayon mirrors MIR1-MIR10 is 58.9°. The maximum range of incident angles onany of mirrors MIR1-MIR10 is 35.6°.

The size of the largest mirror in meridional section is 366 mm. The sizeof the largest mirror in the x-direction is 378 mm.

The mirrors are arranged so that projection objective 2900 contains twopartial objectives: a first partial objective 1010 and a second partialobjective 1020. Accordingly, projection objective 2900 produces threepupil planes and two intermediate images. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, an obscuration stop can be positioned on between mirrors MIR1and MIR2.

First partial objective 1010 has a total of eight mirrors: mirrorsMIR1-MIR8. First partial objective 1010 forms a first intermediate imageZ1 in a position between mirrors MIR6 and MIR7. First partial objective1010 also forms a second intermediate image Z2 in a position at or nearthe position of mirror MIR10. Second partial objective 1020 has a totalof two mirrors: mirrors MIR9 and MIR10. Second partial objective 1020forms an image at or near the position of image plane 102.

An aperture stop B is positioned between mirrors MIR9 and MIR10.

Data for projection objective 2900 is presented in Table 20A and Table20B below. Table 20A presents optical data, while Table 20B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 20A and Table 20B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror MIR1; mirror 2 corresponds tomirror MIR2; mirror 3 corresponds to mirror MIR3; mirror 4 correspondsto mirror MIR4; mirror 5 corresponds to mirror MIR5; mirror 6corresponds to mirror MIR6; mirror 7 corresponds to mirror MIR7; mirror8 corresponds to mirror MIR8; mirror 9 corresponds to mirror MIR9;mirror 10 corresponds to mirror MIR10; STOP corresponds to aperture stopB; and Image corresponds to image plane 102.

TABLE 20A Surface Radius Thickness Mode Object INFINITY 750.158 Mirror 1−3645.207 −700.158 REFL Mirror 2 1388.693 700.158 REFL Mirror 3 421.919−239.680 REFL Mirror 4 928.703 450.888 REFL Mirror 5 −316.927 −82.283REFL Mirror 6 −232.317 253.878 REFL Mirror 7 138.033 −203.878 REFLMirror 8 231.384 424.892 REFL Mirror 9 −631.742 −28.814 REFL STOPINFINITY −179.600 Mirror 10 359.774 228.408 REFL Image INFINITY 0.000

TABLE 20B Surface K A B C D E F G Mirror 1 −6.06373E+01 0.00000E+001.35009E−14 −2.59993E−19 4.09829E−24 −2.02663E−29 −1.37613E−330.00000E+00 Mirror 2 2.31409E+01 0.00000E+00 −1.13367E−14 −1.77547E−196.90094E−24 −1.55471E−28 0.00000E+00 0.00000E+00 Mirror 3 7.66282E+000.00000E+00 −1.35197E−13 −3.76649E−18 1.52791E−22 −1.47257E−260.00000E+00 0.00000E+00 Mirror 4 3.19172E+00 0.00000E+00 −3.50329E−151.79751E−20 2.37312E−26 −3.74208E−31 0.00000E+00 0.00000E+00 Mirror 5−8.19082E−01 0.00000E+00 −3.63599E−15 1.44815E−20 7.93942E−262.39496E−30 0.00000E+00 0.00000E+00 Mirror 6 −2.80654E+00 0.00000E+00−1.90563E−13 7.53932E−18 −1.22667E−22 7.73753E−28 0.00000E+000.00000E+00 Mirror 7 −4.36872E+00 0.00000E+00 −5.57748E−11 9.38288E−15−4.67133E−20 1.96718E−27 1.85277E−26 0.00000E+00 Mirror 8 −7.83804E−020.00000E+00 −3.99246E−15 1.05336E−20 −2.12451E−26 −3.54563E−293.35753E−34 0.00000E+00 Mirror 9 −2.02616E+01 0.00000E+00 3.77305E−13−5.08163E−18 2.24127E−22 −4.81678E−27 8.20784E−32 0.00000E+00 Mirror 106.67169E−01 0.00000E+00 2.85323E−16 −4.15075E−20 6.10237E−25−8.56806E−30 5.42702E−35 0.00000E+00

Referring to FIG. 30, an embodiment of a projection objective 3000includes ten mirrors MIR1-MIR10, and has an image-side numericalaperture of 0.85 at an operating wavelength of 100 nm. MirrorsMIR1-MIR10 are all aspherical mirrors. Projection objective 3000 imagesradiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 41 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is1,942 mm.

Projection objective 3000 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 14.5 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.013λ. Image-side field curvature is 6 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror MIR1 is aconcave mirror; mirror MIR2 is a concave mirror; mirror MIR3 is a convexmirror; mirror MIR4 is a concave mirror; mirror MIR5 is a convex mirror;mirror MIR6 is a concave mirror; mirror MIR7 is a concave mirror; mirrorMIR8 is a concave mirror; mirror MIR9 is a concave mirror; and mirrorMIR10 is a concave mirror.

Mirrors MIR7, MIR8, MIR9 and MIR10 include openings. Mirrors MIR1, MIR2,MIR3, MIR4, MIR5 and MIR6 do not include openings. The resultingobscuration radius that provides a field-independent obscuration is 28%of the aperture radius.

The image-side free working distance is 15 mm. The object-side freeworking distance is 50 mm.

The maximum angle of incidence on mirrors MIR1-MIR10 of a chief ray of acentral field point is 30.0°. The maximum angle of incidence of any rayon mirrors MIR1-MIR10 is 32.4°. The maximum range of incident angles onany of mirrors MIR1-MIR10 is 31.3°.

The size of the largest mirror in meridional section is 650 mm. The sizeof the largest mirror in the x-direction is 704 mm.

The mirrors are arranged so that projection objective 3000 contains fourpartial objectives: a first partial objective 1010, a second partialobjective 1020, a third partial objective 1030, and a fourth partialobjective 1040. Accordingly, projection objective 3000 produces fourpupil planes and three intermediate images. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, an obscuration stop can be positioned on mirror MIR2.

First partial objective 1010 has a total of four mirrors: mirrorsMIR1-MIR4. First partial objective 1010 forms a first intermediate imageZ1 in a position between mirrors MIR4 and MIR5. Second partial objective1020 has a total of two mirrors: mirrors MIR5 and MIR6. Second partialobjective 1020 forms a second intermediate image Z2 in a position at ornear the position of mirror MIR8. Third partial objective 1030 has atotal of two mirrors: mirrors MIR7 and MIR8. Third partial objective1030 forms a third intermediate image Z3 in a position at or near theposition of mirror MIR7. Fourth partial objective 1040 has a total oftwo mirrors: mirrors MIR9 and MIR10. Fourth partial objective 1040 formsan image at or near the position of image plane 102.

An aperture stop B is positioned on or close to mirror MIR2.Alternatively, stop B can also be positioned on mirror MIR7, or betweenmirrors MIR9 and MIR10.

Data for projection objective 3000 is presented in Table 21A and Table21B below. Table 21A presents optical data, while Table 21B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 21A and Table 21B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror MIR1; mirror 2 corresponds tomirror MIR2; mirror 3 corresponds to mirror MIR3; mirror 4 correspondsto mirror MIR4; mirror 5 corresponds to mirror MIR5; mirror 6corresponds to mirror MIR6; mirror 7 corresponds to mirror MIR7; mirror8 corresponds to mirror MIR8; mirror 9 corresponds to mirror MIR9;mirror 10 corresponds to mirror MIR10; STOP corresponds to aperture stopB; and Image corresponds to image plane 102.

TABLE 21A Surface Radius Thickness Mode Object INFINITY 381.457 Mirror 1−1379.982 −331.458 REFL STOP INFINITY 0.000 Mirror 2 862.420 409.088REFL Mirror 3 294.135 −393.417 REFL Mirror 4 674.870 1003.719 REFLMirror 5 159.301 −486.152 REFL Mirror 6 519.366 977.030 REFL Mirror 7−1878.719 −448.038 REFL Mirror 8 805.537 814.366 REFL Mirror 9 −1449.005−316.328 REFL Mirror 10 452.987 331.329 REFL Image INFINITY 0.000

TABLE 21B Surface K A B C D E F G Mirror 1 0.00000E+00 2.55145E−09−6.09305E−14 4.98564E−19 −2.04929E−23 5.33894E−28 0.00000E+000.00000E+00 Mirror 2 0.00000E+00 −2.87984E−10 1.89704E−13 −1.31315E−163.83759E−20 −4.05131E−24 0.00000E+00 0.00000E+00 Mirror 3 0.00000E+00−9.84186E−09 5.83377E−14 1.68182E−18 −3.47385E−23 1.19978E−280.00000E+00 0.00000E+00 Mirror 4 0.00000E+00 −8.72959E−11 2.57957E−16−1.74722E−21 3.35836E−27 −2.85580E−33 0.00000E+00 0.00000E+00 Mirror 50.00000E+00 2.73117E−08 1.12013E−11 9.25229E−16 3.49953E−19 0.00000E+000.00000E+00 0.00000E+00 Mirror 6 0.00000E+00 −2.84379E−10 −4.48476E−16−1.28457E−21 −2.99713E−27 −4.01016E−32 0.00000E+00 0.00000E+00 Mirror 70.00000E+00 −5.31063E−10 2.49955E−16 9.28030E−21 −5.91706E−25−4.04630E−31 0.00000E+00 0.00000E+00 Mirror 8 0.00000E+00 2.32104E−108.53499E−16 2.27404E−21 −3.97444E−27 1.59717E−32 0.00000E+00 0.00000E+00Mirror 9 0.00000E+00 8.99663E−10 3.52918E−15 −4.85346E−21 4.87617E−25−4.02032E−30 2.37898E−35 0.00000E+00 Mirror 10 7.29438E−02 −1.05224E−09−1.45361E−15 4.37512E−21 −1.37373E−25 1.02096E−30 −4.77532E−367.03192E−42

Referring to FIG. 31, an embodiment of a projection objective 3100includes ten mirrors MIR1-MIR10, and has an image-side numericalaperture of 0.9 at an operating wavelength of 100 nm. Mirrors MIR1-MIR10are all aspherical mirrors. Projection objective 3100 images radiationfrom object plane 103 to image plane 102 with a demagnification ratio of8× and a resolution of about 39 nm. The optical axis in relation towhich the projection objective is rotationally symmetric is identifiedas HA, and the overall length of the system from object plane 103 to theimage plane 102, the lengthwise dimension, L, is 1,510 mm.

Projection objective 3100 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 12.5 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.02λ. Image-side field curvature is 5 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror MIR1 is aconvex mirror; mirror MIR2 is a concave mirror; mirror MIR3 is a concavemirror; mirror MIR4 is a convex mirror; mirror MIR5 is a convex mirror;mirror MIR6 is a concave mirror; mirror MIR7 is a convex mirror; mirrorMIR8 is a concave mirror; mirror MIR9 is a concave mirror; and mirrorMIR10 is a concave mirror.

Mirrors MIR7, MIR8, MIR9 and MIR10 include openings. Mirrors MIR1, MIR2,MIR3, MIR4, MIR5 and MIR6 do not include openings. The resultingobscuration radius that provides a field-independent obscuration is 24%of the aperture radius. The image-side free working distance is 20 mm.The object-side free working distance is 120 mm.

The maximum angle of incidence on mirrors MIR1-MIR10 of a chief ray of acentral field point is 36.1°. The maximum angle of incidence of any rayon mirrors MIR1-MIR10 is 44.4°. The maximum range of incident angles onany of mirrors MIR1-MIR10 is 24.2°.

The size of the largest mirror in meridional section is 767 mm. The sizeof the largest mirror in the x-direction is 780 mm.

The mirrors are arranged so that projection objective 3100 containsthree partial objectives: a first partial objective 1010, a secondpartial objective 1020, and a third partial objective 1030. Accordingly,projection objective 3100 produces three pupil planes and twointermediate images. At least one of the pupil planes is accessible forpositioning an aperture stop.

First partial objective 1010 has a total of six mirrors: mirrorsMIR1-MIR6. First partial objective 1010 forms a first intermediate imageZ1 in a position at or near mirror MIR8. Second partial objective 1020has a total of two mirrors: mirrors MIR7 and MIR8. Second partialobjective 1020 forms a second intermediate image Z2 in a position at ornear the position of mirror MIR7. Third partial objective 1030 has atotal of two mirrors: mirrors MIR9 and MIR10. Third partial objective1030 forms an image at or near the position of image plane 102.

Data for projection objective 3100 is presented in Table 22A and Table22B below. Table 22A presents optical data, while Table 22B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 22A and Table 22B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror MIR1; mirror 2 corresponds tomirror MIR2; mirror 3 corresponds to mirror MIR3; mirror 4 correspondsto mirror MIR4; mirror 5 corresponds to mirror MIR5; mirror 6corresponds to mirror MIR6; mirror 7 corresponds to mirror MIR7; mirror8 corresponds to mirror MIR8; mirror 9 corresponds to mirror MIR9;mirror 10 corresponds to mirror MIR10; STOP corresponds to an aperturestop; and Image corresponds to image plane 102.

TABLE 22A Surface Radius Thickness Mode Object INFINITY 245.168 Mirror 1249.951 −124.703 REFL Mirror 2 523.716 501.550 REFL Mirror 3 −667.566−226.847 REFL Mirror 4 −552.364 256.530 REFL Mirror 5 206.660 −297.653REFL Mirror 6 368.135 762.143 REFL STOP INFINITY 0.000 Mirror 7 4031.704−435.563 REFL Mirror 8 577.321 809.677 REFL Mirror 9 −988.316 −324.113REFL Mirror 10 566.943 344.114 REFL Image INFINITY 0.000

TABLE 22B Surface K A B C D E F G Mirror 1 0.00000E+00 −3.11456E−089.16528E−13 −3.54546E−17 8.93385E−22 −1.43705E−26 1.00944E−31−1.28239E−37 Mirror 2 −5.59339E−01 −1.88162E−09 8.43476E−15 −2.59617E−205.48279E−26 −1.28956E−31 6.35331E−38 0.00000E+00 Mirror 3 6.87474E−012.77052E−10 1.40958E−15 4.28911E−21 2.07859E−26 −5.39237E−32 3.55065E−372.29678E−43 Mirror 4 −1.59289E+01 −1.06455E−08 2.59948E−13 −4.36668E−183.82440E−23 8.41820E−29 −3.23510E−33 0.00000E+00 Mirror 5 5.12429E+00−8.25258E−08 −9.24031E−12 −8.33161E−16 1.48317E−19 −4.88263E−232.75394E−26 −6.18092E−30 Mirror 6 −1.39031E−01 3.43126E−10 4.60045E−15−6.53939E−20 5.47733E−24 −2.56664E−28 6.45932E−33 −6.55148E−38 Mirror 75.78570E+02 2.57528E−09 3.83885E−14 −2.02693E−19 −2.80256E−233.79804E−28 −1.15483E−31 −6.06768E−37 Mirror 8 −6.96187E−02 2.19736E−103.72967E−16 1.51513E−21 7.88332E−28 4.72725E−32 −2.42047E−37 7.91050E−43Mirror 9 2.14467E+00 1.04852E−09 2.81763E−15 1.99872E−20 2.86297E−261.14192E−30 −7.63438E−37 4.45766E−42 Mirror 10 5.40700E−01 −5.74797E−10−3.19526E−16 −3.95750E−21 8.93037E−27 −1.25840E−31 8.67177E−37−3.34533E−42

Referring to FIG. 32, projection objective 3200 includes eight mirrorsS1-S6, SK1, and SK2, and has an image-side numerical aperture of 0.7 atan operating wavelength of 100 nm. Mirrors S1-S6, SK1, and SK2 are allaspherical mirrors. Projection objective 3200 images radiation fromobject plane 103 to image plane 102 with a demagnification ratio of 8×and a resolution of about 50 nm. The optical axis in relation to whichthe projection objective is rotationally symmetric is identified as HA,and the overall length of the system from object plane 103 to the imageplane 102, the lengthwise dimension, L, is 1,470 mm.

Projection objective 3200 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 17.5 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.14λ. Image-side field curvature is 125 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S1 is aconcave mirror; mirror S2 is a concave mirror; mirror S3 is a convexmirror; mirror S4 is a concave mirror; mirror S5 is a concave mirror;mirror S6 is a convex mirror; mirror SK1 is a convex mirror; and mirrorSK2 is a concave mirror.

Mirrors SK1 and SK2 include openings. Mirrors S1-S6 do not includeopenings. The resulting obscuration radius that provides afield-independent obscuration is 57% of the aperture radius.

The image-side free working distance is 30 mm. The object-side freeworking distance is 100 mm.

The maximum angle of incidence on mirrors S1-S6, SK1, and SK2, of achief ray of a central field point is 25.4°. The maximum angle ofincidence of any ray on mirrors S1-S6, SK1, and SK2, is 32.4°. Themaximum range of incident angles on any of mirrors S1-S6, SK1, and SK2,is 20.5°.

The size of the largest mirror in meridional section is 945 mm. The sizeof the largest mirror in the x-direction is 960 mm.

The mirrors are arranged so that projection objective 3200 contains twopartial objectives: a first partial objective 1010 and a second partialobjective 1020. Accordingly, projection objective 3200 produces twopupil planes and one intermediate image. At least one of the pupilplanes is accessible for positioning an aperture stop. At least one ofthe pupil planes is accessible for positioning an obscuration stop. Forexample, an obscuration stop can be positioned on mirror S2.

First partial objective 1010 has a total of six mirrors: mirrors S1-S6.First partial objective 1010 forms an intermediate image Z1 in aposition at or near mirror S5. Second partial objective 1020 has a totalof two mirrors: mirrors SK1 and SK2. Second partial objective 1020 formsan image at or near the position of image plane 102.

An aperture stop B is positioned between mirrors SK1 and SK2.

Data for projection objective 3200 is presented in Table 23A and Table23B below. Table 23A presents optical data, while Table 23B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 23A and Table 23B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S1; mirror 2 corresponds tomirror S2; mirror 3 corresponds to mirror S3; mirror 4 corresponds tomirror S4; mirror 5 corresponds to mirror S5; mirror 6 corresponds tomirror S6; mirror 7 corresponds to mirror SK1; and mirror 8 correspondsto mirror SK2.

TABLE 23A Surface Radius Thickness Mode Object INFINITY 450.606 Mirror 1−28568.210 −350.616 REFL Mirror 2 851.174 350.616 REFL Mirror 3 442.020−350.606 REFL Mirror 4 987.208 696.277 REFL Mirror 5 −512.086 −134.752REFL Mirror 6 −273.167 779.239 REFL Mirror 7 348.346 −282.337 REFL STOPINFINITY −362.208 Mirror 8 724.665 674.286 REFL Image INFINITY 0.000

TABLE 23B Surface K A B C D E F G Mirror 1 0.00000E+00 9.08199E−09−6.44794E−13 2.73864E−17 −9.33644E−22 1.62066E−26 0.00000E+000.00000E+00 Mirror 2 0.00000E+00 −3.95755E−09 −4.59326E−14 −7.77764E−181.19180E−21 −6.96128E−26 0.00000E+00 0.00000E+00 Mirror 3 0.00000E+00−2.26321E−08 2.00888E−13 4.01582E−18 −3.30477E−22 7.17255E−270.00000E+00 0.00000E+00 Mirror 4 0.00000E+00 −3.58006E−10 −8.38532E−16−4.42394E−20 4.09594E−25 −2.20889E−30 0.00000E+00 0.00000E+00 Mirror 50.00000E+00 1.82876E−09 3.83573E−15 −1.98419E−19 1.79598E−24−5.45453E−30 0.00000E+00 0.00000E+00 Mirror 6 0.00000E+00 3.72775E−08−9.31689E−13 1.99541E−17 −2.45482E−22 1.70799E−27 0.00000E+000.00000E+00 Mirror 7 0.00000E+00 3.17967E−09 1.39624E−13 2.49821E−181.11591E−22 3.21132E−27 0.00000E+00 0.00000E+00 Mirror 8 0.00000E+009.10620E−12 2.42344E−17 2.73184E−23 2.91015E−28 −7.88285E−34 2.39162E−390.00000E+00

Referring to FIG. 33, an embodiment of a projection objective 3300includes eight mirrors S1-S6, SK1, and SK2, and has an image-sidenumerical aperture of 0.7 at an operating wavelength of 100 nm. MirrorsS1-S6, SK1, and SK2 are all aspherical mirrors. Projection objective3300 images radiation from object plane 103 to image plane 102 with ademagnification ratio of 8× and a resolution of about 50 nm. The opticalaxis in relation to which the projection objective is rotationallysymmetric is identified as HA, and the overall length of the system fromobject plane 103 to the image plane 102, the lengthwise dimension, L, is1,300 mm.

Projection objective 3300 has a ring-segment field. The image-side fieldwidth, d_(x), is 13 mm. The image-side field radius, d_(r), is 12.0 mm.The image-side field length, d_(y), is 1 mm. Image-side W_(rms) is 0.007λ. Image-side field curvature is 8 nm.

The order and curvature of mirrors according to the path of radiationfrom object plane 103 to image plane 102 is as follows: mirror S1 is aconvex mirror; mirror S2 is a concave mirror; mirror S3 is a concavemirror; mirror S4 is a convex mirror; mirror S5 is a convex mirror;mirror S6 is a concave mirror; mirror SK1 is a convex mirror; and mirrorSK2 is a concave mirror.

Mirrors SK1 and SK2 include openings. The opening in mirror SK2 islabeled ASK2. Mirrors S1-S6 do not include openings. The resultingobscuration radius that provides a field-independent obscuration is 34%of the aperture radius.

The image-side free working distance, A, is 30 mm. The object-side freeworking distance is 103 mm.

The maximum angle of incidence on mirrors S1-S6, SK1, and SK2, of achief ray of a central field point is 39.7°. The maximum angle ofincidence of any ray on mirrors S1-S6, SK1, and SK2, is 52.2°. Themaximum range of incident angles on any of mirrors S1-S6, SK1, and SK2,is 23.6°.

The size of the largest mirror in meridional section is 693 mm. The sizeof the largest mirror in the x-direction is 706 mm.

The mirrors are arranged so that projection objective 3300 contains twopartial objectives: a first partial objective 1010 and a second partialobjective 1020. Accordingly, projection objective 3300 produces twopupil planes and one intermediate image. At least one of the pupilplanes is accessible for positioning an aperture stop.

First partial objective 1010 has a total of six mirrors: mirrors S1-S6.First partial objective 1010 forms first intermediate image Z1 in aposition at or near mirror SK2. Second partial objective 1020 has atotal of two mirrors: mirrors SK1 and SK2. Second partial objective 1020forms an image at or near the position of image plane 102.

An aperture stop B is positioned between mirrors SK1 and SK2. Anaperture stop can also be located at a position within first partialobjective 1010. For example, the aperture stop can be positioned closeto or directly on one of the mirrors in first partial objective 1010,such as on mirror S2. The obscuration stop, which defines the pupilobscuration, can likewise be positioned on the same mirror and realizedas an anti-reflection coating, for example.

Data for projection objective 3300 is presented in Table 24A and Table24B below. Table 24A presents optical data, while Table 24B presentsaspherical constants for each of the mirror surfaces. For the purposesof Table 24A and Table 24B, the mirror designations correlate asfollows: mirror 1 corresponds to mirror S1; mirror 2 corresponds tomirror S2; mirror 3 corresponds to mirror S3; mirror 4 corresponds tomirror S4; mirror 5 corresponds to mirror S5; mirror 6 corresponds tomirror S6; mirror 7 corresponds to mirror SK1; and mirror 8 correspondsto mirror SK2.

Other embodiments are in the claims.

TABLE 24A Surface Radius Thickness Mode Object INFINITY 165.327 Mirror 1249.504 −62.783 REFL Mirror 2 343.765 670.215 REFL Mirror 3 −828.212−218.641 REFL Mirror 4 −1067.352 268.921 REFL Mirror 5 332.014 −264.244REFL Mirror 6 338.358 712.058 REFL Mirror 7 1159.033 −164.051 REFL STOPINFINITY −283.661 Mirror 8 567.471 477.708 REFL Image INFINITY 0

TABLE 24B Surface K A B C D E F G Mirror 1 2.99269E−02 0.00000E+00−2.13755E−13 6.46731E−18 −2.49480E−22 5.90564E−27 −7.53450E−320.00000E+00 Mirror 2 −3.44285E−01 0.00000E+00 2.07475E−15 −1.50695E−191.63388E−24 −8.61503E−30 0.00000E+00 0.00000E+00 Mirror 3 2.56188E−010.00000E+00 4.13017E−15 −8.73809E−20 9.49612E−25 −4.79993E−306.26043E−36 0.00000E+00 Mirror 4 3.72134E+01 0.00000E+00 1.17208E−13−1.00755E−17 6.10952E−22 −1.76184E−26 2.51233E−31 0.00000E+00 Mirror 5−2.17361E+00 0.00000E+00 −2.13347E−12 −1.63109E−17 −6.87493E−202.30226E−23 −4.50171E−27 0.00000E+00 Mirror 6 5.10592E−01 0.00000E+004.64944E−15 9.47577E−20 −1.14614E−24 9.25629E−29 8.23956E−34 0.00000E+00Mirror 7 2.30009E+01 1.60457E−09 7.62848E−15 7.32194E−20 1.10925E−24−2.18661E−30 9.19421E−34 0.00000E+00 Mirror 8 1.38025E−01 −4.77315E−11−7.94863E−17 −1.46539E−22 −3.96589E−28 −6.93749E−35 −5.09345E−390.00000E+00

What is claimed is:
 1. A projection objective configured to imageradiation along a path from an object plane of the projection objectiveto an image plane of the projection objective, the projection objectivecomprising: a first partial objective comprising a first mirror withoutan opening to pass the radiation along the path; and a second partialobjective comprising a primary mirror and a secondary mirror, theprimary mirror having an opening to pass the radiation along the path,and the secondary mirror having an opening to pass the radiation alongthe path, wherein: the first mirror is downstream of the object planealong the path; the primary mirror is downstream of the first mirroralong the path; the secondary mirror is downstream of the primary mirroralong the path; the secondary mirror is upstream of the image planealong the path; the primary mirror is geometrically closest to the imageplane; the path intersects a reflective surface of the primary mirror;and a shortest distance between the reflective surface of the primarymirror and the image plane is more than 12 millimeters.
 2. Theprojection objective of claim 1, wherein the shortest distance betweenthe reflective surface of the primary mirror and the image plane is morethan 15 millimeters.
 3. The projection objective of claim 1, wherein theprimary mirror is a concave mirror, and the secondary mirror is aconcave mirror.
 4. The projection objective of claim 1, wherein theprojection objective has an image-side numerical aperture which isgreater than 0.4.
 5. The projection objective of claim 1, wherein thepath intersects a reflective surface of the first mirror, and thereflective surface of the first mirror is off of a principal axis of theprojection objective.
 6. The projection objective of claim 1, whereinthe first partial objective comprises a second mirror without an openingto pass the radiation along the path, the second mirror is downstream ofthe first mirror along the path, and the second mirror is upstream ofthe primary mirror along the path.
 7. The projection objective of claim6, wherein the path intersects a reflective surface of the secondmirror, and the reflective surface of the second mirror is off of aprincipal axis of the projection objective.
 8. The projection objectiveof claim 7, wherein the path intersects a reflective surface of thefirst mirror, and the reflective surface of the first mirror is off ofthe principal axis of the projection objective.
 9. The projectionobjective of claim 1, wherein: the first partial objective comprises asecond mirror, a third mirror and a fourth mirror; the third mirror isdownstream of the second mirror along the path; the fourth mirror isdownstream of the third mirror along the path; and the fourth mirror isupstream of the primary mirror along the path.
 10. The projectionobjective of claim 9, wherein along the path a sequence of the first,second, third and fourth mirrors, respectively, is: concave mirror,convex mirror, convex mirror and concave mirror; convex mirror, concavemirror, convex mirror and concave mirror; concave mirror, concavemirror, convex mirror and concave mirror; or plane mirror, concavemirror, convex mirror and concave mirror.
 11. The projection objectiveof claim 1, wherein an angle of incidence of a chief ray correspondingto a central field point on each mirror in a meridional section of theprojection objective is about 25° or less.
 12. The projection objectiveof claim 1, wherein the second partial objective does not comprise aconvex mirror.
 13. The projection objective of claim 1, wherein theprojection objective comprises at most two convex mirrors.
 14. Theprojection objective of claim 1, wherein, for each mirror of theprojection objective, a distance between the mirror and the object planeis more than 15% of a structural length of the projection objective. 15.The projection objective of claim 1, wherein an entrance pupil of theprojection objective is in front of the object plane of the projectionobjective.
 16. The projection objective of claim 1, wherein an entrancepupil of the projection objective is after the object plane of theprojection objective along the path.
 17. The projection objective ofclaim 1, wherein chief rays of the radiation which travel along the beampath are telecentric at the object plane.
 18. The projection objectiveof claim 1, wherein the projection objective is a microlithographyprojection objective, and the radiation has a wavelength of about 193nm.
 19. The projection objective of claim 1, wherein the projectionobjective is a microlithography projection objective.
 20. An apparatus,comprising: an illumination system; and a projection objectiveconfigured to image radiation along a path from an object plane of theprojection objective to an image plane of the projection objective,comprising: a first partial objective comprising a first mirror withoutan opening to pass the radiation along the path; and a second partialobjective comprising a primary mirror and a secondary mirror, theprimary mirror having an opening to pass the radiation along the path,and the secondary mirror having an opening to pass the radiation alongthe path, wherein: the first mirror is downstream of the object planealong the path; the primary mirror is downstream of the first mirroralong the path; the secondary mirror is downstream of the primary mirroralong the path; the secondary mirror is upstream of the image planealong the path; the primary mirror is geometrically closest to the imageplane; the path intersects a reflective surface of the primary mirror; ashortest distance between the reflective surface of the primary mirrorand the image plane is more than 12 millimeters; and the apparatus is amicrolithography projection exposure apparatus.
 21. The apparatus ofclaim 20, wherein the illumination system comprises a mirror comprisingraster elements.
 22. The apparatus of claim 20, wherein during use ofthe apparatus the illumination system illuminates an object field in theobject plane of the projection objective.
 23. The apparatus of claim 22,wherein the illumination system comprises a mirror comprising rasterelements, and a form of the raster elements substantially corresponds toa form of the object field.
 24. The apparatus of claim 23, wherein theform of the object field is a segment of a ring.
 25. A method of using amicrolithography projection exposure apparatus comprising anillumination system and a projection objective, the method comprising:using the illumination system to illuminate a structure-bearing mask,the structure-bearing mask being in an object field of the projectionobjective; and using the projection objective to image radiation along apath from the mask to a light-sensitive material in an image field ofthe projection objective to image a structure of the mask onto thelight-sensitive material, wherein the projection objective comprises: afirst partial objective comprising a first mirror without an opening topass the radiation along the path; and a second partial objectivecomprising a primary mirror and a secondary mirror, wherein: the primarymirror has an opening to pass the radiation along the path; thesecondary mirror has an opening to pass the radiation along the path;the first mirror is downstream of the object field along the path; theprimary mirror is downstream of the first mirror along the path; thesecondary mirror is downstream of the primary mirror along the path; thesecondary mirror is upstream of the image field along the path; theprimary mirror is geometrically closest to the image field; the pathintersects a reflective surface of the primary mirror; and a shortestdistance between the reflective surface of the primary mirror and theimage field is more than 12 millimeters.